Giant block of foam?

Hi! I thought here might be a good place to ask since I'm not having any luck finding anything on my own.

I'm trying to set up a breeding tank for land hermit crab larvae. I've got a female due with eggs due in a few weeks and after watching how a friend of mine has been raising hers I'm trying to streamline the process to maybe make it a little easier to do daily tasks and keep the tank cycled.

Basically what I'm trying to set up is an in-take sump using a 6" diameter PVC tube with a powerhead, filter media, and heater stuffed inside. It will act as the filter and as a safe place to pull water from for changes. It will also keep the larvae far away from the powerhead and from direct contact with the heater (which is causing problems for my friend).

What I need to find to make it all work is a big block of foam I can use at the top of the pipe to keep the larvae from getting inside. I was thinking that it would be easy to get a large enough block since surely they make it for sumps, but nope, can't find one anywhere!!

It needs to be at least 8 inches in diameter, though 10 inches would be ideal, and at least 6 inches thick so that there will be a gentle enough current that won't let the zoea fall or be sucked inside when the water level is all the way up.

Is there something like this out there?

Is there non-aquarium foam that could be use safely instead?

I'm very grateful for any help or any direction you can point me in!

 

I'm sure you can find something that could work at a craft store. Michaels maybe

 

places that sell pond equipment normally have foam on a roll at different thicknesses. look for it on line i beleive the foam is called "open celled foam"

 

be leery of the company in NY the one sent me my foam about 3 weeks after it was ordered and i had already canceled the order the week before since it was taking to long to receive, did this over the phone and threw a email. than on top of it the foam they sent me was on a roll that was clearly outside and full off debris and starting to denigrate from the sun. it was not a good experience

 

Thank you for the ideas Dingo and pink4miss! After scouring every craft store and pond place in the area I couldn't find anything close to what I was looking for. I ended up rigging up something using filter batting, polyfill and zip ties. Not exactly what I had in mind, but it should work the same.

 

Auto upholstery supply stores or even upholstery shops have tons of foam at different thicknesses