Habitat - Indoor :: under gravel filter

[snazzy]

Hello everyone! I was wondering if I am missing something about under gravel filters. I know not to use sand (too messy and can cause impaction) or little rocks on top (they eat them). But is there any reason not to tie my filter into the under gravel filter without the gravel or sand on top?

What I was thinking was to take filter material (white stringy stuff) and putting it underneath the under-gravel filter screen so the turtles can't get to it. And instead of using air bubbles for water flow to just tie the intake of the tank filter into the under-gravel-less filter. I have fist sized rocks in the tank that I would put on top. Is there something I should know? How often do you think I would have to clean/change the filter material underneath?

Here are my tank stats:
38 gallons (small I know but it is the biggest one that would fit!)
300 gal/h filter but I wonder if this is a lie because it seems to have trouble keeping up with the algae - any advice appreciated
2 RES hatchlings about 1 1/2" each
3 small goldfish (not my choice)
1 catfish looking thing - very small
1 pleco - also small
I assume the turtles will eat all the above eventually which is fine by me.

[grey goose]

It sounds like you're creating a pre-filter, which is fine as long as the turts can't get into it or pull the intake tube off the under gravel end. If they do, it could be dangerous for them as they could get stuck in the intake and drown. When to change the filter floss (white stringy stuff) is largely up to you. I use it in all my canister filters and change it once a month.

[snazzy]

thank you for the reply. Yes, that is what it would be - a pre filter. thanks for the warning about the drowning - I hadn't thought of that. I think it is doubtful near the bottom end as it attaches with a slide mechanism that is hard for even me to move. The part nearer the pump though I will have to think about before I install it to make sure it is a good tight fit.