form use for dish wash as prefilter

[bobcat]

Hi all,
I try to build my emperor 400 HOB a prefilter since its intake is a rare square sharp and it is very hard to find any product at the market to attach to that.
So I buy a dish wash form from the dollar shop. It has a very bright yellow color. Te question is: Is it contains some sort of chemical coating or color that will leech out overtime and harm the fish? Is any one try this before?
Vincent

[bobcat]

HI all,
Just a update, I use it for 3 day in the tank with my six ss and no noticeable negetive effects. The discus got jumpy alittle bit as soon as i put it in. I think because its bright color. They all seem to get used it now.
bobcat