# Water circulation in planted tanks



## STAT 007 (Feb 26, 2003)

My new theory is that modifying HOB filters to reduce surface agitation (to minimize CO2 loss) is counter-productive. I have my Emperor 400 temporarily modified as you described and I've noticed that water circulation is MUCH worse because of it. Because think about how a HOB filter works... It sucks in water from along the back wall of the tank (up from the bottom into the filter intake tube) and outputs it across the top of the water (where the flow then hits the front wall of the tank and drops down), creating a kind of circular flow. But when you modify the output ramp, you're making it suck up water just like before (vertically along the back of the tank), but you're also making it output water directly counter to this (vertically downward, right in front of the intake stream). So essentially you don't get the proper current that you had before. If you watch the little air bubbles move around, you'll see this opposition of currents in the back of the tank where the bubbles TRY to make it into the filter intake (as debris also would), but are knocked away by the falling water flow. This is why I'm starting to shop for a canister filter that will let me minimize surface agitiation, but whose design allows for the placing of the input and output on opposite ends of the tank, thus creating THAT kind of flow pattern.


----------



## Steve Hampton (Jul 22, 2002)

Filtration isn't really a very important issue in a planted tank. Much too much has been made of reducing surface agitation in planted tanks too. While it does help to conserve CO2 in a DIY yeast generated CO2 tank, it can be counterproductive if by doing so you cut down water circulation too.

IME water circulation is extremely critical. I've never seen BGA in any of my tanks that have good water circulation. Water circulation is also critical for proper delivery of nutrients (including CO2) to the plants. It takes good circulation to bring nutrients to the plant and then to be able to penetrate the Prandtl boundary, a fairly thick unstirred layer that surrounds plant leaves. More than any other reason it's that unstirred layer that necessitates keeping CO2 levels so much higher than equilibrium, still without sufficient circulation that unstirred layer isn't easily penetrated. Essentially by increasing water circulation you are decreasing the size of the Prandtl boundary.

So to answer your question, yes IMO you are better off with a powerful canister and underwater spray bar, or doing whatever you can to insure really good circulation.


----------



## STAT 007 (Feb 26, 2003)

Anybody have any good product information links for Eheim canisters? I'm looking to replace my Emperor 400 with an Eheim canister but have no idea which one to get (not only which SIZE to get, but which MODEL also).

I'm also trying to figure out EXACTLY what all they come with and what most people do about input/output options. Eheim's website isn't very good and the product descriptions at Big Al's and Drs. Foster & Smith don't elaborate on just what all you get. I'm primarily talking about intake/output options. I know Eheim has quite a few accessories like a prefilter, surface extractor, return spout, wide jet return, spary bar, blah blah blah. So if somebody could fill me in on what all I'd need to get, that'd be awesome.

Do y'all know of some websites that have more information on intake/output methods with canister Eheims. I'm wondering what the thinking is behind the optional surface extractor and the wide jet return. Also, why do some people use a spray bar for ouput instead of just a hose with a strainer? Thanks a million!


----------



## Momotaro (Feb 21, 2003)

Stat,
I am running an Eheim right now. I really like it. It is a quality piece of equipment and runs dead silent!! I like the Eheim so much, I am thinking of either adding another Pro canister or an Ecco (which model?) to increase water circulation and act a a mechanical filter. I may even run a UV sterilizer of of it.

I am not sure what you mean by input/output options? Give a bit more info or explanation of input/output options, and i might be able to help you figure it out. Do you want to know what is included in the package when you buy the Ehiem?

Mike


----------



## STAT 007 (Feb 26, 2003)

Input/output options, meaning how the water gets sucked from the tank to go to the filter and how the water is returned to the tank. In other words, nozzles.


----------



## Momotaro (Feb 21, 2003)

Stat, it appears you already know your options on the input/output on the Eheims. :wink: 
I use the normal strainer at the intake end and I use a spraybar at the outtake end. I have the spraybar under the surface of the water and at an angle to reduce surface agitation. I like the spraybar. I don't seem to have a strong "blast" coming back into the aquarium. Instead, the output from the filter is a bit more gentle.
I was having a bit of a problem with some surface film created by my Flourite substrate and looked into the surface extractor. Needless to say, I am not using one. 
The prefilter doesn't look like anything special either.
Eheim's website should help you decide which model to select. Try contacting their support staff via email. They will answer any other questions you may have and help you pick the filter that best suits your needs.

Mike


----------



## brandon429 (Mar 29, 2003)

This planted system on the left uses no circulation. It is fully stagnant (but well-lit and fertilized) and supports a small amphibian and several snails. They hold the same crypt wendtii, microsorium, elocharis hairgrass, anubias, hydrocotyle l., pygmy sword and mondo grass that one might use in a larger setup. Im not exactly sure why they run so long and so green with no circulation...but they have been going two years. The one on the right is a terrarium that does use a small waterfall, but the one on the left stays sealed and motionless for weeks in between dosings... I also think that plants with a very thick cuticle such as anubias are very forgiving about the zone Steve is referring to. 

Two years includes the mondo grass, which is usually better off emersed. I fertilize regularly with Kent Pro Grow and MNSupplement, change water every month. Systems are set in the window area, and get bright south-fed sunlight each day. This seems to be the most influencing feature of the experiment, they still bubble every night as saturation is attained and there is also a 13w PC Azoo setup on each bowl for a 12hr photoperiod. There is just something about indirect sunlight that helps these plants retain their red and green colors... if I get too much direct light I notice algae develop on the glass walls.

I definately wouldnt say that unfiltered, uncirculated is the way to go in every system! But in some systems, circulation is less required or maybe not even at all.


----------



## brandon429 (Mar 29, 2003)

This is a daylight shot when the system was about three months old. It is spaced above a candle warmer to induce convection in the little deep sand bed. Roots are now wound around the base of the bowl after about 22 months running.


----------

