Hello all,

New here to aquariumforum.com so hopefully this hasn't been asked/answered already.

LITTLE BACKGROUND:
I just recently 'rescued' two fancy goldfish and a green catfish from being flushed as the owners were moving several states away and had no good way of 'packing" them.

They were originally 'housed' in a standard 10 gallon tank, I've since moved them to a 20gallon long tank, at the same time I upgraded the filtration from a hang on the back style filter (if you want to call it that) to a Rena Filstar xP1 filter system.

Project Ideas
So I'd like to do maybe 2 DIY canister filter projects. I've seen several creations on various web sites, but they never have guidelines as for what size pump should be used.

The first would be used for the little 10gal tank (not sure yet what I'm going to us it for, if anything)

The second setup would be supplemental filter for the big tank. I'm thinking activated carbon / ammonia killing filtration.

Could some one make a recommendation or point me to a formula that I could use to get the correct size pump?

Thank you

Mark

Found on another aquarium forum.

5 times tank size is the 'recommended' pump size

Is this the green catfish?
Tropical Fish for Freshwater Aquariums: Emerald Green Cory Cat

Yup that looks like him.

Cory cats are considered tropical fish which you wouldn't normally keep with goldfish but they do like the lower end of the scale so it might be okay, try reading up or post a question about it. They are also a schooling fish but you don't have space for more fish in your tank which is already heavily stocked.

Well done for the rescue by the way!!

Thanks, since I didn't really get a choice as to what fish I was getting I couldn't very well mix and match 'the perfect combination".

Per the Quick Stats on all three types of fish in the tank, they actually look very compatible. Only Water condition that is different is the KH cat wants 8-10 the gold fish want 4-20. All other conditions are so close it isn't worth 'fighting' over.

I'd like a bigger tank, but I don't see that happening right away. I was nice enough to upgrade them to the 20gallon Long(give them a little bit of swim/breathing room)

I understand your situation. You are doing a good job at doing the best by them that you can. The tank is a little small but I think it's fine if you are careful with water changes etc, particularly if they are not yet full grown. I wouldn't worry about the KH much. You just have to make sure it's not too cold for the cory or too hot for the goldfish. Also watch out that the goldfish don't get large enough to eat the cory.