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Diatom dilemma...


17 Feb 2013

I've posted a couple of times before, and in doing so established that I had fairly low lighting on my high tech setup. As I have LED's I have increased the output and now guess I'm at mid level light.

I have ottos in the tank, who do very well on the profuse diatom/brown algae growth! The faster growing plants are clear but some of the slower ones have it on them. The wood and rocks need a regular scrub to keep it at bay. Tank has been running for four months.

Since I increased the lighting it is less of an issue on the plants, but still forms on the hardscape.

How can I get rid of it? I dose EI, Liquid carbon have high Co2 and good flow. W/C are 75% once a week and 15% every day.

Could it be caused by an area of sand (not sure what type got it at P@H) leeching silicates? Or am I barking up the wrong tree?

Can I get rid of it by overdosing liquid carbon?

Any advice on sorting it out would be much appreciated
It is caused by too much light. Do a search for diatoms and you will find loads of information. Hand removal, blackouts and frequent water changes will help, along with reducing the root cause of lighting. You may also want to review your flow/distribution.

Thanks for the reply. When I first started the tank I had read that the lights should be on for 12hrs a day and nitrate was the enemy:facepalm: Once things started going wrong I did a bit of reading around, found UKAPS and thanks to many of your own posts and those of others on the site, got my set up 'inline' with what is recommended I've had it running this way for the last six weeks.

Could the current problem be a hangover from the bad start I had?
Would you dismiss this theory about the sand too?
Thanks for your help.
Yes it could be related to the bad start, as well as to poor flow and distribution, but mainly is has to do with too much light. Diatoms sometimes appear at tank startup and then go away all by themselves a few weeks later, never to be seen again - except if the hobbyists continues to pummel the tank with too much light. It's probable that your LED output is stronger than you think, so really you should be thinking about reducing it to very low output values like 15% for a few weeks to allow the tank to recover.

Diatoms do not really care about sand. If that were true then tanks with sand would constantly have diatoms, while tanks without sand would suffer less. In real life there is no correlation between which tank has sand and which of them have diatoms. Diatoms appear regardless of the substrate and their appearance is mostly related to the fact that the sediment has not developed the bacterial colonies, so the bio-chemistry of the sediment is unstable. If you keep the lighting intensity very low then this will allow the tank to recover.

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Clonitza, I stopped testing anything about 6 weeks ago, and I tend to look at the drop checker as this sort of measures PH anyway doesn't it? The water out of my tap is PH 7 in the tank before Co2 comes on it is PH7.8, and by lights on (after 3hrs of Co2) PH is 6.8

Ceg4048, Okay I'll forget about the sand then. I'm pretty sure my flow and distribution are good. Spraybar running full length of rear wall, and a koralia 900 in the middle all facing the front glass. Ceramic diffuser is positioned 8" below the koralia at substrate level and I see bubbles blowing around all parts of the tank.

I had thought lighting, and had dipped it to 50% output, but that was also with a 180min fade in/out either side of peak output so not actually 50% for very long, I had it that way for two weeks and things did not seem to improve -and some of my plants stopped growing as quickly and got more diatoms, but maybe it was not dim enough or two weeks was not long enough.

One other thing is the room is fairly light as it has a big window in, but the tank is on the opposite wall and never gets direct sun. But I did see a set up you had in a conservatory, so decided I was being over concerned about the one window. That said I'd imagine some photosynthesis is taking place in this ambient light, and maybe the diatoms exploit this? I don't fancy bricking up the windows though! I had read that diatom problems can be more common in low light set ups, does this make any sense?

Probably a daft question but what are these diatoms anyway? Are they simple 'plant' cells? Why are they brown and not green (full of chlorophyll?) if they indicate too much light?

Thanks for the help, I hope I can knock them on the head and get my plants looking super healthy:)
Hi mate,
I wouldn't worry too much about light from the window. You simply have too much light from your LED and it might be on for too long. Its very easy to solve this problem, but people are always in denial when it come to light. We have been programmed to think that all problems are cured by adding more light and we are always afraid that we don't have enough light, when in fact we always have way too much light. In nature, when plants are exposed to high light, they are normally at least semi-exposed to atmosphere, and so the leaves have access to plenty of CO2. When the plants are fully submerged the water is usually dark and murky. Some plants live submerged in clear water but the water is often fed by underground springs high in dissolved CO2.

Diatoms are probably the most important algal species we have today. A significant portion of the yearly Oxygen production of the planet is generated by the over 10,000 species of diatoms. They are mostly oceanic, but they are also plentiful in freshwater and in sediments. Their chloroplast cells are yellow or brown, not green as in other species. This is because the cells contain a very high percentage of the pigment known as Fucoxanthin, which is in a class of pigments called Xanthophylls. Fucoxanthin is a highly efficient pigment which absorbs light from blue all the way to yellow. Xanthophyll is the pigment that gives egg yolk it's yellow color.

Some studies have supposedly shown that human consumption of Fucoxanthin increases fat burn, so they sell this stuff in pill form as a weight loss solution. Kelp and other seaweed are also high in Fucoxanthin, so it would be better to eat the dried plant.

Diatoms also build their own shells (called a frustule) using a hydrated form of silicon dioxide, which effectively is a kind of organic glass. For years, hobbyists have been told that because sand is made of silicates, and since the diatomic shells are silicon based, then it follows that silicates due to sand, or silicates in the tap water will trigger diatomic blooms, but this is a myth. The same people try to tell us long ago that nitrates in the water trigger green algae, and as we know, this is also a myth.

Viewed under Scanning Electron Microscope, diatoms are simply beautiful. Check Dennis Kunkel Microscopy for more images:

Thanks for the info! That link to Dennis Kunkel has some great pictures on it, shame something that looks so good up close just looks like brown sludge to us!

So it seems I am back at reducing light to control/limit the diatom growth. I'm already being very finicky with keeping everything clean and doing lots of water changes so hopefully once I cut the light I will be rid of them.

If I go down the reduce intensity of output route to something as dim looking as 15% am I okay to keep the CO2 high, or would I need to dial this back for any reason? Same question goes for ferts I suppose.

If I just shorten the photo period to say 5hrs (currently on for 7) I could just start the CO2 a little later than at present so it is still on 3hrs before lights on to get Lime green DC, and keep the ferts the same as now?

Does either option seem preferable in terms of likely success?

Does this approach work against most of the different types of algae people tend to get in aquariums then?

Thanks for taking the time to help me out with this, it has been driving me slightly mad:crazy:
Finding this thread really helpful. I'm in exactly the same position as you Reuben.

Injecting co2, E.I dosing and adding liquid carbon. Drop checker is lime green at lights on and lights are on for 7 hours a day. flow is good with a spray bar along the back wall of the tank but i'm getting diatoms as well.

I was also thinking of dropping my lighting to 5 hours a day and adjusting the co2 start time, maybe even extending it slightly if the fish can take it.

What i'm wanting to know is, is there a minimum length of time the lights should be on for?
Is having the lights on for less than 5 hours detrimental to the plants?

I'm not to bothered about the plants growing quickly, I'd much rather have slower growth but very healthy plants.
Besides what's already mentioned, high bioload and traces of ammonia can trigger diatoms too.
It's possible the filtration isn't enough for the tank size/amount if fish, melting plants, debris, too much mulm in the filter, etc...
Cleaning the tank and adding extra filtration to deal with those unmeasurable traces of ammonia may help too. 4 months is a long time to have diatoms.
If I go down the reduce intensity of output route to something as dim looking as 15% am I okay to keep the CO2 high, or would I need to dial this back for any reason? Same question goes for ferts I suppose.
Hi Reuben,
CO2 and nutrients are the fuel used to make food. Ask yourself this question: Is it OK to have a full tank of petrol in the car even if the car will always be driven on "B" roads far below the speed limit?

Fundamentally, the reason we have plant problems is that we are driving the car on the motorway far above the speed limit and we are running out of petrol.

When you have problems in your tank consider that the reason is that there is insufficient food caused by insufficient fuel with which to make that food. This is a fundamental principle that people seem to have difficulty grasping. Plants do not grow because of light. They grow because of food. The light is the oven used to make the food.

The higher the intensity of the light, the higher the temperature of the oven. In the car analogy, the higher the speed of the car. So when you have lots of light you are careening down the motorway out of control just like those police car chase real life videos. When you reduce the intensity then the car is being driven at a more controllable speed. You will arrive at your destination, but it will take longer and you are less likely to have a collision. If you reduce the temperature of the oven the food will take longer to cook, but there is less chance of burning the meal to a crisp.

If you can hold to these analogies then the solutions to the problems become so obvious. To cook the food, the oven requires some minimum temperature. Presently, you are far above that minimum temperature, the food is burning, smoke is billowing from the oven and yet you are worried that there may be problems if you lower the temperature of the oven. The joyrider in the stolen vehicle wonders what he needs to do to make the car go faster.

Seriously consider these analogies and it won't take long to understand the state of affairs in planted tanks. As an historical perspective, the planted tank scene really took off with the advent of CO2 injection. Conversely, people started having major troubles with the advent of T5 lighting which is brighter than T8.

Therefore, when we suffer health problems in our tanks the very first response should be to reduce the demand for nutrients/CO2 by reducing the light, and at the same time, to increase the availability of CO2/nutrients. This gives us the best chance of recuperation. We really never need to worry about the implications of lowered light intensity, because it was high intensity that got us into trouble in the first place.

Here is one of the major differences between higher plants and algae:
Algae require more light to survive than do higher plants. The reason? Simple. Plants have vast storage facilities. They collect CO2 and nutrients, make food and store the food in grain silos. Some of the food they eat of course, but as long as they make more food than they consume, the extra will always be stored for later hard times. The lower the intensity of the light, the slower the food is produced, but again, as long as the rate of food production exceeds the rate of food consumption there is never a problem.

On the other hand, algae don't really have an elaborate storage facility. Algae live in the here and now. They cannot depend on a food bank so when food runs out they starve. Their advantage though is that they are very small, very lean and don't have very complex systems which need to be fed. So, the higher the light the faster they can grow and reproduce. Since they are small they don't really need as much CO2 or nutrients. Think about how much of the diatoms you collect when you are cleaning the tank. Although it looks messy and they seem to be everywhere, when you collect all the algae in your hand and pull them out of the water there is actually not that much weight compared to say, a stem of Ludwigia. Algae are thousands of times smaller than plants and so require thousands of times less nutrients and CO2 than plants do. That's why it's so crazy when people talk about how adding more nutrients causes algae. Algae really don't care how much CO2/nutrition is in the water. They only care about how much light there is. It is the plants that worry about having lager amounts of CO2/nutrition because they require lots of it, especially if the lighting is high.

So, within this context, think about a blackout. When you do a 3 or 4 day blackout, the plants are not too perturbed because they have stored large quantities of food, so they just carry on. But Algae quickly use up what little food reserves they have and then they starve because no light is available to produce food.

If you perform the blackout but then return to high lighting without fixing CO2/nutrients afterward, what happens? Algal spores bloom again and plants suffer again. But if you return to high CO2, high nutrition and low lighting, then the plants are not stressed, they make food, replenish their food reserves and carry on. The low light prevents the spores from blooming.

So, if you keep the lighting very low then it doesn't really matter how long the photoperiod is. The plants continue on in a slow pace until some weeks pass when they are strong and healthy enough to make physiological changes which enable them to adapt to higher light and to make better use of the higher light.

If you keep the same high intensity then the damage is still being done to the plants and diatoms are still loving it, so you have to guess or experiment with photoperiod length to determine how long it should be. I have absolutely no idea whether 5 hours of 50% intensity will be OK. No idea at all. I'm much more confident though that blackout plus 10%-15% will kick the diatoms in the groin. It's a certainty...

Hi Clive,

Thanks for the above, I did have some grasp of this notion but maybe not the confidence/certainty in it to follow through with the logic of it:confused:.

As the level of diatoms is fairly small, I am hopeful I might not need to do a blackout, but if my current actions don't work I will do that.

I have now reduced the photo period to five hours and lowered the intensity. CO2 and fertz will remain at current levels so hopefully this car will not be running out of fuel any time soon;).

I guess one reason I was resistant to following through with this route it that when I look in the featured journals I see folks doing very well with high light levels- George's current tank for example. Now while I appreciate these people are more experienced and better able to see and correct problems before they happen, I had been thinking that in much the same way you said how 'sand is not related as not all who have sand get diatoms', these high light tanks got me thinking maybe light isn't the key either as not all who have high light get diatoms?

I realise there are probably a whole bunch of reasons why these high light level tanks don't get diatoms/algae take overs, but what do you suppose the main reasons would be? Is it that they set up right from the start, so things don't go off track as easily?

Also once/if I get rid of the diatom growth, should I then slowly increase light levels again or would this just lead me back to where I am now?

You have a photo which has L.aromatica and P.stellatus in it. When I saw this photo I couldn't believe the L.aromatica was the same plant as mine as your looks completely different - way better! What aspect do you think go it looking so lush, or was in a combination of things?

I'll report back on progress once I've given the changes time to take effect. Thanks again for your input.
I realise there are probably a whole bunch of reasons why these high light level tanks don't get diatoms/algae take overs, but what do you suppose the main reasons would be? Is it that they set up right from the start, so things don't go off track as easily?
Yes there are lots of reasons that those tanks don't get algae, and that's fundamentally because the plants are healthy. In order to support the higher lighting levels the plants must be healthy enough to make the physical adaptations, and the only way to get them to that point is to give them the time and nutrition to make those adaptations. When flow, distribution, and CO2 are good, when the sediment and filter are mature, and when the plants adapt to being submersed and are fully functional underwater then the lighting can be increased without risk. The problem is that few people actually understand what good flow, good distribution and good CO2 actually means in the practical sense. People just try to follow some formula such as "Oh, my DC is green, everything must be OK" or "I looked at my test kit and the readings indicate that the tank is cycled". The people who own those highly lit tanks know better and they do not follow the one-size-fits-all approach. They keep the lighting low, flow high as well as CO2/nutrient attention early on. They keep up with water changes and maintenance. They give the tank time to mature so that the microorganism infrastructure can support higher environmental stress levels, without triggering blooms. You can get there without too much fuss but you just have to be patient and treat the tank as if the inhabitants are in an intensive care unit. Light causes stress. It is a electromagnetic wave, the same as Gamma Rays or Microwaves, just not as dangerous, but it still does damage to the plant. If the plants are healthy, they can easily repair the damage and then use the light to their advantage. If they are weak then the light causes more damage than it is useful.

Also once/if I get rid of the diatom growth, should I then slowly increase light levels again or would this just lead me back to where I am now?
You should only do that if you can confirm that your flow/CO2 is good and that your maintenance is good.

You have a photo which has L.aromatica and P.stellatus in it. When I saw this photo I couldn't believe the L.aromatica was the same plant as mine as your looks completely different - way better! What aspect do you think go it looking so lush, or was in a combination of things?
Yes, it's a combination of all things mentioned. In many of the cases the lighting was actually very high, as much as 1/2 kilowatt of T5 over the tank, but I do not startup the tank with Klingon levels like that. I work my way up to it, and I make damned sure that CO2 and flow improve with each bump of the light. Also, I make sure that the lighting is dim for the first few hours of the photoperiod, then I allow more lights come on. It takes a lot of time in the morning for the plants to get their chemistry going, for enzyme production to be optimized. They really have a hard time at the beginning of the photoperiod. Imagine that every morning you were dragged out of bed and thrown on a chain gang in the middle of the desert without even having breakfast. That's what we do to our plants when we zap them with megawatts first thing in the morning. High lighting is best applied gradually. I'm always telling people to reduce their lighting but I use more light than probably anyone on the planet. On the other side of the ledger, I probably use more nutrients and CO2 than anyone as well. I do more massive water changes than anyone I know, and I keep the tank scrupulously clean and free of any organic waste by scrubbing the leaves with my fingers and removing any debris.
High light has a cost. It's not free. You really have to be on top of you Ps and Qs, and so that's why it would be better for you to abandon high light aspirations for the momemt and just learn how to grow plants with reduced lighting. Believe me, you can still have problems even with reduced lighting and so having high light makes things double tough.

After you understand the tank more then you can level up just like in video gaming. What this tank is telling you is that if you are getting diatoms 4 months in, then you are asking for additional trouble before you have acquired the skills to troubleshoot.

Okay, that all sounds good. I'll stick with the plan you've suggested. Once I have the problems reined in, and the plants are looking stronger I may start to slowly increase light. When I set this tank up I did everything wrong, not out of ignorance but because I had read books on the subject which have turned out to be of little value.

I think that I am now on top of my game in terms of flow, CO2, tank cleaning/maintenance, fertilisers. But if I understand you correctly I need to develop a stronger foundation of plant health before I add any extra pressures to their systems, by blasting more light their way. Thanks again for the advice.
Well, as it is a month on I thought I'd update progress here.

The action I took was to drop the photo period to 6 hrs, set both units to a max of 20% output with a 180 min ramp time after lights on and before lights off. This resulted in plant growth going fairly static compared to before, with the exception of Crypt wendtii which have grown hugely over the course of the month. I have kept up regular water changes and have started to does EI at higher levels maybe 2x standard recipes.

The main benefit so far is I now have no diatom growth at all:thumbup: and hardly any other algae growth to speak of (tiny bit of bba on some wood). I've been amazed at how the stones which needed a regular scrub before are squeaky clean, algae free.

So whilst I am content with the new lay of the land, I would like to improve plant health and slightly speed growth up. If all the other plants were as healthy as my crypts I'd be happy.

Can I start to tinker with adding a bit more light or would it be wiser to give things a bit more time - time for the plants to 'strengthen'?

I've no idea how long plants take to adapt and recover in new (low light) conditions, will the lower light slow this 'repair' ability as well as growth?

For example if a sickly plant was transferred into 'ideal' conditions would it make adaptations to it's new setting and thrive with in say, a week or a month?

Donation made to UKAPS as a thanks for the help thus far.

Thanks very much for the donation. I assure you that it's greatly appreciated.

You can tinker as much as you want now that you have a better understanding of cause and effect. The reason people continue to have problems is because of a lack of understanding, so they blame the failures (as well as successes) on the wrong causal factors. If you increase the lighting and later incur a fault, you will know that the tank was not ready for that amount of increased energy.

It's always a good idea to increase the CO2/flow/distribution prior to a lighting increase. This will produce the best performance increase.

When the spectral energy is increased, plants make the adjustment in terms of the pigment population and allocation. Normally, the chlorophyll population and density is decreased and so the plant actually becomes less efficient. When the spectral energy is decreased, the plants typically become more efficient at gathering light.

You would be well advised to remember that adding more light does not make a plant necessarily healthier. Adding more light increases the food production rate and allows a higher level of carbohydrates to become available, but higher levels of carbohydrates can only happen if more carbon is made available. Therefore, for any plant, adding more light without allowing greater access to CO2 + water causes a decrease in health. For terrestrial plants, think about a desert. There is plenty of light, and plenty of CO2 - but there is a shortage of water, so those plants cannot make carbohydrates. For aquatic plants, the ingredient that is always is short supply is Carbon in the form of CO2.

It's really not possible to predict how quickly a plant can recover because much depends on the genetic predisposition of the plant, the actual availability of Carbon and nutrients, as well as what the exact PAR values are. As you mentioned, under the same conditions, a crypt has improved growth, yet other plants in the same tank have not accelerated as quickly, so there is a wide variety of performance possibilities just due the type of plant.

Hi, Thanks for the info. I think I will be very cautious about increasing the light much more then. Whilst all algae has totally gone now, most plants are still looking a bit jaded and tired on close inspection.

All the reading I'm doing leads me to keep thinking that my Co2 isn't good enough. Would using an in-line diffuser instead of the in-tank ceramic one I have, make the Co2 available in a form that was more 'dissolved' and therefore easier for the plants to uptake (assuming the total concentration by the two methods was the same eg 35ppm) I know my Co2 level is high (and if I try to raise it further the fish don't like it) plus I'm 2x dosing LC at lights on. So maybe its flow? But all the plants are wafting about, the jets of water from the spray bar (visible when I drop the water line) hit the front glass with a fair bit of force! Plus I have a Koralia (same flow direction as spray bar). I'm not sure what to tinker with to alter flow? I could remove filter media, one basket is chock full of purigen (500g) and zeolite (200g), so I could remove half of that and no doubt get more flow, but the flow does already look strong -to me at least. I could post a vid I suppose.

Maybe the only problem I have is lack of patience:lol:

Just want to get it look top notch now though!
In exactly the same boat as you, my tank sounds identical.
spray bar, power heads, ei dosing and dosing a hefty amount of glut. lights are on 5hrs a day. while there isn't much algae at all the plants just look a bit drab
Co2 is injected via a fluval ceramic diffuser. I'm thinking the diffuser just isn't efficient enough for my tank, obviously getting a lot of waste with bubbles reaching the surface.

I've just finished building a co2 reactor which i'll hook up tomorrow and let you know how I get on. I'm really hoping it will make an improvement.
In-line devices typically work better than in-tank devices, especially as the tank size increase. Tanks larger than about 40 gallons see an improvement with in-line reactors. The Up atomizers are popular and so are the DIY versions. Ed Seeley and Foxfish have DIY reactor threads around here. I assume you are doing frequent water changes? When you do the water changes, get in there with your hands and gently remove the slimy bio-film buildup from the leaves. That will help improve uptake efficiency.

Any visual examples you could post would be helpful. :)