billw813

Hi all, I would like to say that this my first adventure into the world of Fish. I have read several books and many articles on the internet. By far I have gained more knowledge reading on this sight than any other. But still some things are not as clear as I would like them.
Filtration:
I have been looking at the Eheim 2215 Classic canister filter for my tank. It says it is rated for a 92gal tank, I understand about water displacement and by the time the substraight and decor are in I might only have 77gals. of water, and flows at 164 GPH. My questions is that I thought the filter was supposed to filter the tank water 4x per hour. ie: 20gal tank should have a filter that flows at 80gph and a 90gal tank should have a filter that flows at 360gph.

I have a 90 gal tank.

I am thinking of having 6 to 8 Bala Sharks in the tank. Would the tank be large enough for them?

Tumbleweed

First off welcome to fishlore. I am unclear as to what tank size you have so that info would help. 2nd the general rule of thumb is 1inch of fish per gallon. And since Bala sharks can get up to about 1 foot long when full grow you would need to hace a 100gal tank to house 8 bala sharks. As for the 4 times per hour of water cycling in the tank. In my opion this is only really needed in a heavily stocked tank. Worse case senerio is you will have to do more frequent water changes the less filtration you have. ie 3 20-30% water changes a month vs. 2 20-30% water changes a month.

sirdarksol

Larger fish don't fit the "1 inch per gallon" guideline. The larger a fish gets, the amount of waste it produces increases geometrically. Also, the amount of space it needs to feel secure increases. I think that 8 Bala sharks in a 100g would feel pretty stressed. Fishlore lists Balas as requiring a 55g to start with, and suggests a much larger tank.

As far as filtration goes, I've never been great at remembering the numbers, so I just go by what the production company says. The gph partially depends on the amount of filter media. A canister that forces the water through a large amount of filter needs a lower gph rating than a HOB that passively "pushes" water through a single 1" sheet of biological media. One thing, though, is that I always go with the lower end, if they give a range ("good for 40-60 gallons" would mean "good for 40 gallons" to me), or supplement the filtration in some way if they only give one tank size.

COBettaCouple

Welcome to Fishlore.

I've not had canister filters, but I know our members who have can help you out.

The 90g is big enough for Balas, probably 6 at the most.