Water turnover formula

[twong727]

I have a 125 gallon Malawi tank currently using one Eheim 2217 (rated as 264 gph) and one Eheim 2215 (rated as 164 gph). I currently have about 20 fish ranging from 1 inch to 4 inches. I will get more fish for sure, but I will do it slowly.

When I got the 125g tank (used) 2 months ago the seller threw in a Rena XP4 canister filter for free (rated as 450 gph). It was not in good condition (3 of the locks were partially broken). However when I tried it out this weekend the locks were working OK with no leaks and the motor was working fine (not as quiet as my Eheim but still acceptable).

Long story short I now have 3 canister filters at my disposal for my 125g tank. Which should I use to maximize water quality without over paying on my electricity bill? Is there any reason I should use all 3?

I usually do 50% water change once every 2 weeks.

Thanks for feedback in advance.

Tony

[verbal]

I think your biggest bang for your buck in filter performance/electric cost would be a HOB filter and a canister combo.

I would tend toward overfiltering. The financial difference of losing(or even treating) 1 or 2 fish, or getting an extra spawn or tow with cleaner water will outweigh the extra costs.

[twong727]

Not familiar with HOB, I thought I need to buy custom foam pads/cartridges for HOB to fit the space which are usually overpriced?

[pitdogg2]

HOB = Hang on back filter.

personally i would use all 3. As i said in one of your previous post use one of the Ehiem's as a bio-filter. Fill it full of Matrix,siporax or any number of good bio-media. I personally use a XP3 and a Magnum350 on my 75gal tanks. Not only are the XP3's full of matrix(20ppi sponges in the first basket) but they also exhust to bio-wheels that came with the Magnum350's.