Looking for some direction regarding submerged pond foam

[bucknetbucky]

First of all let me start by saying hello and thank you in advance to all those that are helping a new comer like myself. I have been reading a lot on here and learning more and more all the time.

So for the question (I have searched but cannot find a concrete answer). I have started my first go at an encloser for a couple of firebelly's which is half and half. The devide is spray foam (black pond type ans yes it is sealed and holding the water). I would like to know if I need to cover the submerged area of foam or is it OK to leave this plain?

Thank You in advance.