Start here:
http://algaescrubber.zohosites.com/
Tap water with top of tank dump bucket Inland Aquatics ATS...I can understand every problem you just described.
The first thing to look at is that you likely don't need that huge of a screen, the old conversion thought process was for every "unit area" (which is right now for a vertical screen, 12 sq in of screen lit on both sides per cube of food fed per day) you would need:
2x that area for a vertical scrubber lit only on one side (and you wouldn't be able to let it grow as long)
4x that area for a horizontal scrubber
So if you fed 1 cube/day, that's 12 sq in for vertical double-sided, 24 sq in for vertical single-sided, 48 sq in for horizontal
One could argue that the horizontal number is specific to a Adey-style dump bucket and that a static horizontal scrubber could be 8x. The one you are using is actually pretty expensive and about as good as you're going to get for a dump bucket scrubber. But, IMO, it's a throwback. The vertical scrubbers are better on many levels.
I would put it in a sump at minimum though