Is there such thing as too much filtration?

[Davo]

I have a 420 litre tank (4x2x2) with a Eheim 2088 and a 2213 for filtration. I was looking at buying a Eheim 2250 for the tank and getting rid of either the 2088 or the 2215.

If I get the 2050 will it combined with the 2088 or the 2215 be excessive filtration?

Regards,
Dave.

[TeeFM]

I dont think there is such a thing as "excessive filtration" as long as you can afford it. However, this can cause excessive water current in the tank...your discus may not like it.

[wickedglass]

TeeFM has it in a package, there's no such thing as "excessive" when it comes to filtration. Although you could talk about "superfluous" filtration, ie extra filtration that isn't really needed.
It is possible to hook up canister filters in series if you're inclined towards more filtration area and only power one of them if you're getting too much current, but personally I'd be leaning more towards using one of your eheims and a generic cheap filter when doing this, instead of 2 eheims.
On average most people would recommend a turnover of your tankwater at about 6 times per hour. , so in your tank that would be about 2400 lph turnover. One of my tanks is a 4 x 2 x 1 1/2 and has a canister which is rated at 1200 lph and I have no problems at all.

[Robdog]

I don't think there can be excessive filtration but I also agree with the current factor.

Would this equation work? More filtration= less water changes

[TeeFM]

I dont believe "more filtration = less waer changes". The reason you change water is to dilute nitrate level in the tank, which cannot be digested by bacteria in your filter.

More filtration may = clear water from mechanical filtration point of view.