I was advised that by having a sump, it would affect my CO2 levels...presumably because the CO2 would be removed as soon as the tank water hit the sump filter media ?

My tank is 5x2x2 and the sump is an old 48x15x18 tank converted into a 3 stage, up and over type sump.

Could this be avoided by having the pipe from the tank to the sump submersed in the "wet section" of the sump....so there'd be no splashing or trickling over media....it would just be submerged wet media.

Does that sound clear enough

Any other problems you can see happenning with sumps ?

Many thanks

Andy

A sump will work just fine as long as it's sealed or as close to sealed as you can get it. And you minimize water turbulence. Normally the place with the highest loss is the overflow.

A sump is not nearly as bad for CO2 loss as is a wet/dry.

I use a full wet/dry on my 100gallon, I go through a 10lb CO2 every 3-4 months at high CO2 levels, 30-40ppm. I don't care about the additional CO2 loss, it is cheap to refill.

So no, it won't affect your CO2 levels if you have effective Co2 reactor, you just have to use a little higher bubble rate.