High water turnover - discuss :)

Hiya Matt,
Yeah, powerheads can help quite a bit - there's no denying it whatsoever, but haven't you noticed the trend towards removing things from the tank and to reduce clutter in the tank - inline heaters, inline diffusers, glass pipework etc? This aesthetic movement is away from clunkiness and towards a more streamlined and minimalist look.

Once you determine how much extra circulation you need then you have to pick the right size powerhead, and that can be unsightly. Remember we talked about how to achieve various flow patterns as well? It isn't just the added flow throughput but the circulation lines to eliminate dead spots, so this means you have to really get creative about how and where you position the pumps. That means that now your aquascaping has to encompass the geometric solution of fluid dynamics as well as art. No thanks. Have you seen Barrs latest 180G effort? It looks fantastic until your eyes wonder over to the rocket propelled grenade launcher on the left, ugh...http://www.barrreport.com/general-plant ... ar-13.html

That does illustrate however how committed he is to flow and I believe if you read through the thread his total flow is a massive 4000 LPH. The larger the tank the more committed you need to be about flow. CO2 becomes more problematic as tank size increases but is important in all sizes.

The other thing to consider is that the bigger the pump rating of a filter the more filtration you have. More biomedia means more bacteria and that means better NH4 control. We should be committed to getting NH4 outta there as quickly as possible especially if the tank is highly lit.

I've use lower flow, powerhead augmentation and bigger filters and the hands down best solution from an algae, plant growth as well as from an aesthetics standpoint I've found is massive filtration. Remember that my tank is lit by 1/2 kilowatt of CF T5 with reflectors and sits in a conservatory open to sunlight. It is extremely well lit. The difference in algal blooms was immediate as soon as I upgraded the filtration.

Now does this mean that you won't get algae if you have massive filtration? Hardly - a high filtered tank is subject to the same rules, so that poor dosing or too much light or poor CO2 will cause trouble. Does that mean you can't be successful with lower flow? No, not at all, many do. What we're saying is that massive filtration is your ally. It means that if you do suffer an algae attack then it's loads easier to get rid of when the throughput is higher because you have a bigger bacterial army as well as better nutrient delivery. What it means is that you can upgrade your lighting with less trepidation because CO2 delivery is more efficient with higher flow. You can also overstock more with less fear - so there are lots of benefits of higher filtration besides the added flow. George is even more fanatic than I am. I think he follows the 20X rule...

Cheers,

 

Hi Matt

For the record, I think the filtration, flow and circulation 'new-school thinking' is one of the biggest developments in the hi-tech planted tank hobby, behind CO2.

Bigger is better, simple as that.

20x turnover rule is good for me for smaller tanks under 100 litre. 10x for bigger tanks. Jeremy Gay and I joked about this actually. One should not go for the 10x turnover rule, but the 10x rated rule i.e. a filter rated for a 1000 litre tank should be used for a 100 litre tank.

I think it's also important to combine the good flow and circulation with good biological filtration to further help minimise potential algae isssues. So I'd always opt for bigger and better filters, over filter+powerhead.

BTW I've had good results with less i.e. Juwel internal filter. But this was low light and I highly suspect that with high lighting etc. then it wouldn't be enough. And that's a very important point. In lower lit tanks, the importance of getting all the CO2 etc. around the tank isn't as important.

So Matt, what would I do in your tank? Probably have 2x big externals with a combined rated flow of around 2400+lph.

Those were the days. Well, the days before some jumped-up, over-enthusiastic geek called George Farmer came along and preached about the 'dark arts' of NPK dosing etc.

 

I added a powerhead to my tank and its doing the trick, its really a small internal filter which as a sponge and all, works pretty well for my size tank and since then I haven't had any more problems, things just grow like weeds. Its well hidden behind the plants and you can't really see it unless you go looking for it as you probably can see on the photos from my tank.
I will replace my external eventually but I will wait until it breaks or something like that.

 

James/Ed,
I've thought about your points and while they do seem reasonable, they bring up more questions than they answer. Now, remember my arguments are based on premise that NH4 + light cause algae. If you don't buy that premise then the arguments are not valid.

James, I remember that urea experiment you did and Barr brought up the strong possibility that the filter and sediment bacteria were reducing the ammonia in the urea via enzymatic action of urease. That would mean the bacterial reaction to NH4 is very quick, and that suppression of NH4 spikes are attributed to rapid nitrification.

I guess I also disagree with the assessment that "...tiny amounts of ammonia..." are produced in a planted tank. I would argue that the ammonia production is high and is constant simply by virtue of metabolism. Just consider the amount of ammonia generated during a tank cycling. That ammonia production rate never stops, and in fact it accelerates when we add plants and animals and food. It's just that we measure a low concentration level because the NH4/NO2 is being processed. Barr brought up the point in that thread that if you thought ammonia production in a tank was low, all you need do is to turn off your filter for a while and see the results.

All we have to do is to look at our empirical evidence. How many reports are there of algal blooms in a planted tank? Algae has become almost a central theme. A contributing factor? Ammonia production not attenuated by the available bacterial colonies. So what you say is true, that low stable levels of ammonia keep the blooms at bay but how does one achieve low stable levels? Its certainly not stable when one feeds the fish for example. Metabolic rates and organic waste decay are not really all that stable as the plants grow or are trimmed, or when water is changed. I would argue that an aquarium is the least stable aquatic environment known to man. If sintered glass media or sponges function as we think they do, by making space available for hosting bacteria, then more space means that a rise in NH4 allows these germs to increase their population more easily. If less space is available would this not affect the rate of bacterial population increase necessary to consume an NH4 spike?

We observe that detritus and organic waste buildup stifle a filter by blocking the pores of the media reducing the bacterial population. Detritus sitting in the filter breaks down into ammonia which fails to be processed by the colony. The result is often BGA if filter maintenance is not performed. It seems obvious to me that if you have more filter capacity to begin with the likelihood of this condition is reduced. Maintenance is still required, obviously but you have more biomedia and space to begin with so the effect is lessened and your margin of error is widened.

I also don't buy the assumption that bacterial populations are necessarily limited by NH4 availability. Of course this could be the case under certain conditions but we really haven't measured populations versus NH4 concentration so this would be speculative. Also it's not certain that all the NH4 in a volume of water is removed during a single pass though the filter. So if I connect two filters in series this assumption would mean that bacteria colonies would be established in the first filter and not the second. Clearly, while the available space is not completely filled in both filters the available space represents a potential that affects the speed at which the population can increase. This population agility allows absorption of ammonia spikes which occur constantly.

Again, I refer to the urea thread in which Barr referenced a list of K.R. Reddy journals. Further investigation reveals that bacteria, like plants and animals require more than just Nitrogen to prosper. They require Carbon and Phosphorus as well as other ingredients. So a bacterial population could easily be limited by the availability of other nutrients. Like Nitrogen the other nutrients must be in the right form for them to digest. Some bacterial species can obtain their nutrients in a variety of forms (i.e. organic and/or inorganic) or they can use substitute elements for their biological processes, such as Sulfur in lieu of Oxygen. Other species are less agile and suffer die off if their specific needs aren't met.

We all agree that flow is definitely King, but I view the extra filtration capacity as a "shock absorber" that processes ammonia spikes which helps to suppress algal blooms. It is difficult to quantify though how much of one's success is due to the extra flow versus the extra filtration capacity. :?

Cheers,

 

Yes, but you'll never see that flow rate in real life, especially if you fill it with biomedia.

I should add that the only real thing I have against powerheads is their lack of aesthetics. As mentioned, they are a much cheaper alternative and if you don't mind the looks, or if you have a clever way to hide them then they give you a lot of flexibility as you can point them in whatever desired direction. In the final analysis if economics forces you to choose between healthy plants with ugly thunderball jet packs versus less healthy plants with clean tank lines, well, go for the jet pack... 8)

Cheers,