If I may add a little info on the "green board" I'd like to shed a little light. For years we have had what we called in the industry green board. It used to be the only green board and it is used in bathroom normally in shower enclosures or around tub surrounds. Things of that nature that were later going to have a tile, or some other substrate installed over it.
In today's society there is a huge misconception of what it really is, and how it is supposed to be used.
Not to bore anyone with technical facts, but here are two from the National Gypsum Company.
National Gypsum Company said:
What type of gypsum board would you recommend for use on the walls and ceiling of my indoor swimming enclosure?
None. Gypsum board (including green board) is NOT recommended for use where there will be direct exposure to water or continuous high humidity conditions such as found in saunas, steam rooms, gang shower rooms or swimming pool enclosures, per ASTM C890. A cementatious tile backer, such as PermaBase®, or the use of a Portland cement based plaster system should be considered.
My home was in a flood and the gypsum board in my basement was exposed to flood water. Do I have to replace the gypsum board in my basement?
Yes, gypsum board that has been soaked by floodwater can be a permanent health hazard. When the gypsum board finally dries, there will still be mud and contaminants dried inside and to the gypsum board.
Also in terms of it being mold resistant, the product is only as good as what you have either put on top of it like a mold resistant paint, but if it is up against say a normal 2x4 or 2x6 wall, mold will form at the wood in high levels of moisture so it's not quite as cut and dry as one would think by the way it is advertised.
I am a semi retired General contractor/master craftsman and have done 50+ fish rooms all over the country. Currently working on my own ATM and unless I was doing say a tile mosaic on a wall, I wouldn't spend the extra 4 or 5 bucks a sheet to use green board. It's a little stronger than normal, but in terms of water resistant, it's just not. The paint you use over it is Key.
As far as things I would be looking for near the fish area? Where, or how close is the main electrical panel, and how close are we to the sump in the basement. So long as those two items are fairly close, anything can be done.
