Filtration rate vs algae growth?

[SleepyAries]

Hi guys,
been reading the last few lastest threads toking abt ways of removing/curing algae problems and was wondering if filtration rate from the filter play any parts in algae growth or algae death ? done a search around here, but seems there r only threads on pple discussin abt solely on filtration mediums, wat sort of mediums, how u should placed each mediums...etc, etc..but not any discussion on filtration rate. Can anyone guide me to any if there is ?

i dun really know how to phase my questions, but roughly,
i wish to find out if filtration rate affect algae growth or death in any ways ? normally, one would choose a filter with filtration rate which will suits the volume of the tank he owns, but wat are the advantages and disadvantages of choosin a bigger filter with higher filtration rate, comparing to choosing a smaller filter, with lower filtration rate ? one example i could think of, is from NA. i find that Mr Chan's tanks are using small filters (think 2235 and equivalence) for his 4ft tanks, but his tanks are always algae free. ( i tot 2235 filtration rate will not be able to support a 4ft tank?)
i read somewhere where it says algae (not sure which type...BBA/brush ?)will tends to first form around areas where flow of water is fast, ie: along the path of water from your filter output. how true is this ?

i understand proper maintenace and dosage of fertilizer is definately a MUST to control alage growth, but say if proper maintenace and dosage, does filtration contribute as a factor too ?

thanks..

[vinz]

Perhaps a better term would be circulation instead of filtration rate.

I have found and read that circulation can affect algae. But it is part of the bigger picture, that is proper fertilisation, light and CO2.

Plants cannot move to their food. The food has to come to them... hence you need to get good circulation in the tank to get the ferts (which includes CO2) to the plants.

OTOH, if the water is moving too fast, plants can't absorb the food fast enough.

Go borrow a copy of Diana Walstad's Ecology of the Planted Aquarium from the library. There's a chapter in there that explains this (if I remember correctly)

Ever wondered why certain algaes only grow in some parts of the tank... given that conditions in other parts of the tank are similar... like lighting or shading?

Circulation also helps to bring waste like nitrites and ammonia into the filter. With poor circulation, these will accumulate in stagnant areas, while fertilisers are unable to make they way into these areas.

Two things that can effect circulation are flow rate and placement of the filter outlets. Circulation can be improved by installing power heads in strategic locations.

Your main aim would be complete circulation.

I've notice BBA favours 2 types of places... fast flow areas near the water outlets and stagnant areas under foreground plants.

I had the latter problem this year, on 2 patches of E. tennelus. One patch cleared completely in about 2 weeks when I turned my rainbar to point directly at it. The other patch was still infested. Eventually, I got sick of the thick E tennelus and BBA under them and ripped up all of them. BBA never came back.

[budak]

I wouldn't advise using LFS tanks as a model. The owners spend lots of time to change the water and maintain the setups, so their filters aren't necessarily a good indicator.

A large number of wild habitats for aquatic plants are streams with medium to strong current. The idea is that the current sends fresh oxygen, CO2 and nutrients for the plant (in fact, I see wild plants ranging from crypts to hairgrass to rotalas doing splendidly in very high flow patches). BBA seems like to like strong currents too, but the standard remedy of maintaining consistently high CO2 levels (25 mg/l or more) seems to work for me. Stagnant water and tanks with deadspots are observed by many to be linked with BGA

As vinz said, the filter has its role in the nitrification, as well as water circulation. Quite a few of use here use filters that are 1-2 sizes larger than the standard manufacturer recommendations for our tanks, one reason being the inevitability of clogs after prolonged usage. The other reason being water circulation throughout the tank. For myself, I find that a Eheim 2228 isn't sufficient for my 3.5 ft tank (250 l), so I am using an additional powerhead (1,000l/h) which sends currents to parts the filter outfeed doesn't reach. I use a 2224 for my 2 ft tank, which seems just about right.

I also have (search for the article) a 1 ft tank without filter. But as the tank gets no fert, has slow growing plants, hardly any water change and has lots of algae-eating shrimp, it's no problem.

[IUnknown]

I've seen this with hair algae on the glass. I had the outlet of my canister filter pointed at the front glass of the tank. You could see where the high flow of the water prevented the algae from attaching to the glass. The glass on the left was covered with hair algae. The thing is, it might help with certain types of algae, but for others it would not.

What I want to know is how much is too much filtration. I don't understand the whole, plants need slower currents to take up the nutrients (I need to reread Walstad's chapter). I mean think of oxygen with humans, even if you stick your head out of your car its still available, just harder to suck in (bad analogy?). My eheim 2224 turns my 20 gallon over 8-9 times an hour.

[SleepyAries]

hi...

i got the same doubt as IUnknown. How much is consider too much ?
correct me if i'm wrong, from wat vinz and budak says, can i say this :
if under good fertilization regene (or regeon.or how u spell tat... ), good lights and good co2,

Low circuation:
1 > plants will grow well, but due to low circulation, certain areas will have algae growth becos excess fert may "trap" themselves in "some" corners where current cant bring them away, and thus, algae grows there. (like in vinz thread, he mentioned areas like area under plants ?)

High circulation:
1 > plants will NOT grow soo well...becos they cant absorb the fert fast enough, thus resulting in excess fert circulating around the tanks, and due to this, algaes feed on this xcess fert ...

am i right to say so ?

[PeterGwee]

Generally speaking, as long as the filter circulates the tank volume 2-3 times per hour its fine. The important thing is gentle even current throughout the tank rather than blasting it all over. A spraybar attachment at the bottom back of the tank for the filter return line is good. The nutrient and CO2 rich water returns at the bottom of the tank where it slowly rises through the plant leaves and is uptaken by the plant leaves. (More contact time and good even flow).

Regards
Peter Gwee

[budak]

Actually my view is that a fairly strong current is good for the plants..... i am not convinced of the view that plants are unable to "snatch" nutrients from a strong current, thus allowing algae to get the fert instead...... perhaps someone more botanically trained can clarify this??? The idea that I get is that strong currents provide foremost a fresh supply of dissolved gases (both Co2 and O2) for the plant to photosynthesise as well as metabolise.

For algae, you can't generalise.... I have seen BGA grow in both well-circulated and stagnant tanks...... whereas BBA noticably grows well in strong currents. So while a well-circulated tank is certainly desirable, other factors (Co2, lighting, fert) will come into play in algae control.

[vinz]

I think depends from plant to plant. Some have adapted to growing in fast flowing water. Some in stagnant. Some probably don't care.

It's pretty subjective. I have yet to see numbers about what's too fast and what's not. Filter flow rate is not a good measurement... that's a very localised effect.

For example, when brand new, my 2250 was churning out 1000litres/hr for my 600 litre tank... less then 2x the tank volume, yet plants at the other end of the 6ft tank were dancing.