Doubling light amount over an established set up.

Hi,
im currently running a 180l fluval studio 900 tank, with standard 2x 39w ho t5 lighting unit, pressurised c02 system, daily fert regime etc. The lighting unit is a hagen glo and i have had good results to date. However as my plant mass has increased, light is becoming less readily available at the substrate. Also these lighing units dont offer the best spread of light which is not fully illuminating the tank surface. This combination of issues is resulting in less than optimum lighting both at substrate level for carpeting species and at the rear surface where stems are situated. Probably also worth mentioning is that there are also glass covers between the lights and water which i presume will reduce intensity to a point.
My questions are;
if i were to add another hagen glo light unit over the tank to spread the light more evenly at the front and rear of the tank am i asking for trouble. The tank has been running for over 6 months and is established with no current algae issues. This would be taking the lighting upto 156w over 180l which is a lot, but with the light spread being so poor are the same rules applicable?
Also the light comes with the option of suspending the unit via two inbuilt hooks, so it could, reluctantly, be raised higher to increase light spread, but in turn reduce depth penetration (and also blind me when sitting viewing the tank, or watching tv etc).
The current light is sat on runners on an aluminium frame, so the light can be moved to any position along the width of the tank. Could i rotate the lighting position from a front bias and then towards a rear bias to effectively intensify lighting over a given point in the tank. If this was a feasible option what rotation period would be best, daily changes, or during any given day alter the position throughout the day, much like the sun moves in nature? This option would be a pain, and raises another question of is it the light intensity that the plants like or photoperiod?
Which of my options is the best? :?
Thanks,
Ady.

Hello,
If you want to add more light to your tank, then do it because deep down in your heart, you are really a megawatt loving Klingon . Don't justify it using the plants as an excuse, because the plants don't really need more light. All aquatic plants are essentially low light plants when submerged. The leaves at the top, which are exposed to higher PAR levels, actually reduce their photosynthetic efficiency and produce pigments which fluoresce and reflect the high light energy to protect themselves from high photonic energy. On the other hand, the leaves at the bottom improve their photosynthetic efficiency by allocating more chlorophyll per square inch within those leaves.

In thick heavy undergrowth, these lower leaves also improve their CO2 uptake efficiency, however, there is much more margin for light gathering than there is for CO2 gathering, so there is really not much to gain by pummeling the tank with more photon torpedoes. Firstly because this will then require more CO2 and flow and then this will result in the leaves at the top growing that much faster and broader, causing that much more blockage of both light and CO2 to the leaves below.

Cheers,

I dont quite understand what you are saying about your present lights not illuminating the surface?
Is this because the lights are too close - if so you could consider an open top tank with overhead lighting?

There is no doubt that 2 x T5 is adequate, you only have to look at some of the amazing tanks on this forum powered by 2 x T5.

There are some exception - some folk with more specialist equipment like trickle filters, sumps & needle wheel pumps that can saturate the water with oxygen & c02, & lots of experience & understanding can then offer more light but thesse folk also spend a lot of time maintaining the tanks.....

I say if you want more light then do it, but be prepared for the consequences i.e. higher CO2 and nutrient requirement, more maintenance, higher risk of algae. It can be a valuable learning experience and I understand the desire to try out new techniques.

Probably the best way to increase light intensity without major issue is to do so gradually i.e. have the second luminaire on a seperate timer to come on for small photoperiods, and gradually increase over some weeks. Keep an eye on the plants for signs of deficiencies and algae. Doing so gradually gives the plants time to adjust to the higher light and consequential demands.

Mark had success with 2 x T5 but with using an additional midday burst with metal halides without adjusting his CO2 and ferts. I'm not sure how long this was undertaken for though, and would assume that in the long-term the plants will have been crying out for more food! Could be worth speaking to Mark directly.

Hi,
thanks for the replies.
I thought i would ask the question before i went ahead and did it to ascertain the possible repercussions of doubling the light and seek advice on alternative routes. Maybe in hindsight the topic title should have been light spread, issue or not?, as adding more light is only one solution to the perceived problem.

ceg4048 said:

If you want to add more light to your tank, then do it because deep down in your heart, you are really a megawatt loving Klingon . Don't justify it using the plants as an excuse, because the plants don't really need more light.

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foxfish said:

There is no doubt that 2 x T5 is adequate, you only have to look at some of the amazing tanks on this forum powered by 2 x T5.

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Im quite happy with running just 2 t5's and its clear to see the results gained by people such as Mark Evans, however i was also looking for answers regarding light spread. Mark runs a rather expensive Geisemann light unit which he has stated has excellent reflectors and light spread. My unit is a hagen glo with the two tubes sat within 1cm of each other along the centre of the tank. You can see what i mean on the link below:
http://www.practicalfishkeeping.co.uk/c ... p?sid=4023

foxfish said:

dont quite understand what you are saying about your present lights not illuminating the surface?
Is this because the lights are too close - if so you could consider an open top tank with overhead lighting?

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Exactly foxfish, however as i said

Ady34 said:

Also the light comes with the option of suspending the unit via two inbuilt hooks, so it could, reluctantly, be raised higher to increase light spread, but in turn reduce depth penetration (and also blind me when sitting viewing the tank, or watching tv etc).

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But im trying to see if i can use an alternative method than suspending above or raising the light unit as i dont want too much light 'spilling' into the room, or to loose the depth of penetration. I seem to remember Andy H had a similar issue in his 'Lounge tank' journal, with an ADA solar unit 'blinding' his family!! From what i remember he ended up selling the unit.

ceg4048 said:

there is much more margin for light gathering than there is for CO2 gathering, so there is really not much to gain by pummeling the tank with more photon torpedoes. Firstly because this will then require more CO2 and flow and then this will result in the leaves at the top growing that much faster and broader, causing that much more blockage of both light and CO2 to the leaves below.

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Yes i can appreciate this and i am aware that 2 t5 lights are sufficient for good results, i would think though, perhaps incorrectly, that a better spread of light would be better at reducing shading issues, thus optimising the light available. I could trim my current plants to allow more light penetration, however you want good plant mass and thinning too much spoils the aesthetics. I was also alluding to an idea of moving the current light unit over the width of the tank

Ady34 said:

The current light is sat on runners on an aluminium frame, so the light can be moved to any position along the width of the tank. Could i rotate the lighting position from a front bias and then towards a rear bias to effectively intensify lighting over a given point in the tank. If this was a feasible option what rotation period would be best, daily changes, or during any given day alter the position throughout the day, much like the sun moves in nature?

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Any advice on this as an alternative would be appreciated.

George Farmer said:

Probably the best way to increase light intensity without major issue is to do so gradually i.e. have the second luminaire on a seperate timer to come on for small photoperiods, and gradually increase over some weeks. Keep an eye on the plants for signs of deficiencies and algae. Doing so gradually gives the plants time to adjust to the higher light and consequential demands.

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Makes sense, but the only issue with this however would be the lighting unit type. If i were to get the same unit as im currently using (which i would want to for aesthetic reasons), i would have one unit towards the front and one towards the rear thus whilst using small photoperiods the issue of light spread would be worse ie, only light at the front or the back unless both units were on.
I have looked into the ATI Sunpower range of dimmable light units, which would be ideal. They run 4 x 39w t5, but have two seperate wiring loops so lights 1 & 3 and lights 2 & 4 could be put on seperate timers. Because the lights are spread better you could effectively get a good spread from just two lights and ramp it up midday burst for extra if you needed, or alternatively just lower the light intensity when all four are running with the inbuilt dimmer but getting excellent even light spread. These units are expensive though and i havnt £300+ to spend, hence looking into adding a less expensive extra glo unit.

George Farmer said:

I say if you want more light then do it

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George Farmer said:

It can be a valuable learning experience and I understand the desire to try out new techniques

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Appreciated George, however I think maybe ill hang fire and stick with what i have for now,

George Farmer said:

be prepared for the consequences i.e. higher CO2 and nutrient requirement, more maintenance, higher risk of algae.

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ceg4048 said:

because this will then require more CO2 and flow

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these reasons are enough to stop me, as i still havnt mastered the C02 and nutrient requirements for this set up yet!
I just thought that adding and extra unit would help yield better results. The eleocharis parvula at the foreground of my tank is gradually being thinned in areas arount the crypts which i put down to shading, which consequently i thought i could correct with better light distribution. I dont want to thin the crypts too much as i like the look of the more dense growth. Also i thought it may help provide for the stems at the rear, where the surface light is reduced due to the poor spread on the current single glo light unit. On my current set up, adding another lighting unit was the easiest way of doing this taking into account that i dont want to blind the kids, myself or the wife by raising the light higher above the water surface, and i cant really afford a more adaptable lighting unit such as the dimmable ATI Sunpower..... oh well its christmas again soon!!!
Thanks,
Cheerio,
Ady.

Ady34 said:

...I just thought that adding and extra unit would help yield better results. The eleocharis parvula at the foreground of my tank is gradually being thinned in areas arount the crypts which i put down to shading, which consequently i thought i could correct with better light distribution..

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Almost all structural issues with submerged plants are due to poor CO2. I don't know why everyone insists that plants rotting, thinning and dropping leaves must be because there is not enough light. Your tank has much more plant mass than it did months ago, both above the substrate and below. More plant mass needs more CO2. The additional plant mass also blocks more flow. This has absolutely nothing to do with the spread of light, which is strictly an aesthetic issue. If you don't like the shading and shadows that's one thing, but as I said earlier. leaves in shade behave like shade plants and leaves in high light behave like open savannah plants. Both configurations are present in the plant at the same time without conflict. If you are losing plant mass however, then this is most probably a result of CO2 starvation, and because this is by far the most likely then it follows that you should attack the area of CO2 injection rate and/or flow rate first, BEFORE spending money on more light. Get a better filter or increase the gas rate and see if that solves your problem first. There is a 95% probability that your Elocharis is suffering blocked flow and poor CO2 uptake.

Cheers,

I agree i probably still need to master the c02, and until then wont move on to higher light levels.

Ady34 said:

George Farmer wrote:
be prepared for the consequences i.e. higher CO2 and nutrient requirement, more maintenance, higher risk of algae.
ceg4048 wrote:
because this will then require more CO2 and flow
these reasons are enough to stop me, as i still havnt mastered the C02 and nutrient requirements for this set up yet!

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Indeed!

ceg4048 said:

There is a 95% probability that your Elocharis is suffering blocked flow and poor CO2 uptake.

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I am in no way trying to argue a point i know little about, just trying to understand more, however the flow and c02 distribution are at their highest where the eleocharis is as there is a koralia nano pointing downwards towards it, and the c02 diffuser releases its bubbles into the path of the powerhead. Admittedly i am still tweaking the c02, but am getting a lime green dc approx 4hrs into the photoperiod, a slightly darker green at lights on. Im trying to up it, to get lime green when lights on, however last time i tried this towards the end of c02 period the fish were struggling! Should i be aiming for lime green at lights on?

ceg4048 said:

If you don't like the shading and shadows that's one thing, but as I said earlier. leaves in shade behave like shade plants and leaves in high light behave like open savannah plants.

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Surely though some plants just require a minimum amount of light to photosynthesise, and not all will adapt to low light levels.
Out of interest do plants take up directly the c02 bubbles, or the dissolved c02 in the water?
Thanks again,
Cheerio,
Ady.

You should aim for a lime color at lights on. CO2 is very difficult to get right, especially when there are fish in the tank. That's why I always try to dissuade people from putting fish in the tank until after they have CO2 figured out. The most important time for CO2 is at lights on. 4 hours into the photoperiod is too late, although the more robust plants are less likely to suffer. What you can do is to turn the gas off earlier. After 4 or 5 hours the need for high CO2 is not as critical as it is earlier in the photoperiod. This helps to give the fish a break.

Ady34 said:

Surely though some plants just require a minimum amount of light to photosynthesise, and not all will adapt to low light levels.

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AS I said, all plants will adapt to low lighting levels. The effect of light is to accelerate growth. Plants do not need high light. The minimum level of light required to produce food is called the Light Compensation Point (LCP). However, the PAR value for LCP is somewhere between 20-30 micromoles, a value which is easily exceeded in all of our tanks, especially the ones using T5, Halides and LED, and even with shading. Carpet plants may have a high LCP than say, ferns or mosses, but it is not so much higher that you need to double the light input.

Ady34 said:

...do plants take up directly the c02 bubbles, or the dissolved c02 in the water?

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Contact with gaseous CO2 appears to result in better performance, but just having bubbles does not tell the whole story. The bubbles must actually make contact with the leaf and they must be small such as in a mist. Just having lage bubbles blown about the tank does not work because these large bubbles have a higher bouyancy and they just escape the tank. In that case it's better to have the gas in solution.

Cheers,

The problem I have with the various misting methods is that the mist always seems very determined to reach for the surface & disappear into the atmosphere!
Its not so bad if you are really jetting the water around but then you get false readings in the drop checker!
I am still using a needle wheel pump but passing the water through a reactor to rid me of the mist
Anyhow, personally I much prefer the lower light option as I just find the whole tank easier to manage.
I like the more gentle approach for my fish & I prefer to see gentle plant movement in preference to testing my fish's ability to survive & watching a washing machine LOL
I love to see the successful high lighting tanks & have been there myself so would not actually criticise anyone for experimenting with lighting - it just that I have been there, done that & decided it was too stressful :?

Thanks Ceg, thats answered most of my questions.

ceg4048 said:

You should aim for a lime color at lights on. CO2 is very difficult to get right, especially when there are fish in the tank. That's why I always try to dissuade people from putting fish in the tank until after they have CO2 figured out. The most important time for CO2 is at lights on. 4 hours into the photoperiod is too late, although the more robust plants are less likely to suffer. What you can do is to turn the gas off earlier. After 4 or 5 hours the need for high CO2 is not as critical as it is earlier in the photoperiod. This helps to give the fish a break.

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Im currently switching c02 on 2.5 hours pre lights on and off 2 hrs before lights off to try and get a steady introduction. Would you advise starting the c02 earlier (as it does reach lime green) or simply increase the rate of introduction slightly, or both?
At the moment pearling only starts approx 5 hrs into the photoperiod, which is 7.5 hrs after c02 injection starts.

ceg4048 said:

AS I said, all plants will adapt to low lighting levels. The effect of light is to accelerate growth. Plants do not need high light.

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Ok, ill concentrate on the c02, and watch my plants from there.

ceg4048 said:

Contact with gaseous CO2 appears to result in better performance, but just having bubbles does not tell the whole story. The bubbles must actually make contact with the leaf and they must be small such as in a mist. Just having lage bubbles blown about the tank does not work because these large bubbles have a higher bouyancy and they just escape the tank. In that case it's better to have the gas in solution.

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I suppose either way thats where flow and distribution come in!
Unfortunately i cant add a spraybar set up to my tank without engineering a custom fit to the pre drilled pipework. I know your an advocate of that system as ive read in other sub forums, however i think my flow pattern manages to circulate water to most parts of the tank relitively successfully.
Thank you for your patience, im sure it must get a little tedious relaying the same points, but its much appreciated. That should do for me now!
Cheerio,
Ady.

foxfish said:

The problem I have with the various misting methods is that the mist always seems very determined to reach for the surface & disappear into the atmosphere!
Its not so bad if you are really jetting the water around but then you get false readings in the drop checker!
I am still using a needle wheel pump but passing the water through a reactor to rid me of the mist
Anyhow, personally I much prefer the lower light option as I just find the whole tank easier to manage.
I like the more gentle approach for my fish & I prefer to see gentle plant movement in preference to testing my fish's ability to survive & watching a washing machine LOL
I love to see the successful high lighting tanks & have been there myself so would not actually criticise anyone for experimenting with lighting - it just that I have been there, done that & decided it was too stressful :?

Click to expand...

Yeah, i know what you mean and ive often thought about trying a reactor system as i dont like the bubbles.... they spoil the view! However now i have the koralia in alongside the G6 im managing a flow pattern which pushes most of the mist downwards, along the tank, then another jet directed towards the front of the tank pushes the c02 down again, rolling it along the substrate and back across to the koralia which sucks it back in and down again! The filter also draws some c02 in and distributes along the rear of the tank also. I think ill master getting the c02 spot on before i try other techniques, its taken me long enough to get this somewhere near! The dc is in the furthest most corner away from bubbles, probably in the area of least flow also, so its probably sited as best it can be for accuracy, although im sure they do have limitations where misting is used.
Im sure a tank full of stems on high light is ridiculous to manage. In some respects this is why most of my plants initially were less demanding species aimed for longer term, sustainable managability.... kids and jobs dont allow for overly fussy tank management, or 6 monthly rescapes!
I too dont like to see the fish battling torrents, its stressful rather than relaxing, but its nice when you have some quieter areas to see the fish excercising in areas of higher flow knowing that they can take a break if they fancy.
Im sure ill be trying all sorts of scaping techniques over the years, and this first attempt is a learning curve aimed at teaching me the basics before i move onwards and upwards.
Thanks for the interest and replies,
Cheerio,
Ady.

Ady34 said:

...Im currently switching c02 on 2.5 hours pre lights on and off 2 hrs before lights off to try and get a steady introduction. Would you advise starting the c02 earlier (as it does reach lime green) or simply increase the rate of introduction slightly, or both?

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You'll need to do a combination of both probably. A good rule of thumb is to get pearling about an hour into the photoperiod. 5 hours means that the CO2 levels are weak at a time when it should be strong.

Cheers,

Cheers, on 3 hrs pre lights, upped rate slightly, off 2.5 hrs before lights off.. will monitor!