Originally Posted by flight50
You know, I actually thought about this last night before I went to bed,lol. The main reason was to replace my current AquaClear 300s in which I run two. AquaClear 300 are rated for up to 70 gal. The Eheims are rated up to 65gal. Both are over the 4 times per hour threshold. Considering I ran two, might a well continue. Nothing wrong with more filtration. In my tank I have some fast growing and easy discarded leafed plants.
Another reason is in case one fails, the other can take up the slack until I can get to it. Just like my Heaters, I run two. Less stress on the environment upon failure. With the Eheims it appears that I can regulate the flow with the valving system it have vs the AC filters so if I need to tune it down I can. Besides, there have been many setups I have seen running 2-3 canister filters.
Last reason is because Big Als has a sale going on. I have been waiting for a canister sale for awhile now. I can get two 2213s for 69 a piece or the 2215 for 99 a pop. In my case, two small filters are better than one big one.
I guess I was too brief last time, and didn't make myself clear; my apology for this, and missing the tank size which I now see
. Two filters is not better, and it may or may not be detrimental.
Live plants have a major role in filtration. And I accept your comment that your present tank is balanced and healthy. If a 55g is full of plants and they are thriving, and has the minimal fish load you mention, it is a good example of where less frequent water changes are needed. However, it is a mistake for any of us to assume that the fish are in their best condition just because appearance is one way or another. Fish in nature have water changing around them every second of their lives, and we cannot even hope to reach this standard. But we do our best. Fish are putting stuff, which I call crud, into the water and no filter we can provide will handle any of this. Plants can, but it is a very delicate balance. So this crud remains there until we remove it via a water change.
Back to the filters, two filters will do nothing more beneficial than one that is adequate for the aquarium. And by adequate I mean it provides what the system requires. And this is determined by many factors: the fish species and number, plant species and number, water parameters, temperature, maintenance. And all of these factors contribute to the aquarium's balance biologically. There are some natural planted tank hobbyists who advocate no filter at all, and this can work if the aquarium is balanced. I like a filter in each tank, be it ever so minimal. First, it helps to move the water around which removes suspended particulate matter from the plant leaves into the water column and then through the filter media where it can be removed; second, this movement brings nutrients to the leaves and roots of the plants; third, it helps maintain a even temperature. Too much water movement is detrimental to plants via the second issue mentioned. And too much movement also inhibits biological filtration in the filter itself, though this is more a concern when live plants are not present and one relies on bacteria.
There is no benefit to over-filtration--aqnd by this term I mean filtration beyond what the system requires. There may be a detriment, depending. And I haven't even touched on the fish. Forest fish do not appreciate excessive water movement, it literally wears them out and causes stress. This also depends upon the extent of the movement. I'm being general in all this.