Questions - Need some input

I noticed that my black and white brittle star hasn't been as active as usual recently, and last night I noticed that one of his legs seemed like it had about a half inch piece missing when he was close to the glass. I was a bit worried, but today it got much, much worse. I saw what appear to be 1-2 inch long pieces of brittle star leg all over the tank, some still moving a bit. The main disc had one leg attached but it looked like the top had come open too. It was as if the whole star just fell ...

I don't think I'm getting enough flow, but my pumps gph seems to be high enough. What would you do if you had a 90 gallon tank with 2 Koralia Evo 1050 powerheads and a return pump? The ph's are positioned in the back corners both facing the middle of the front pane of glass, and the return is on the back right side pointed straight left. Would you redirect pumps? Add pumps? Keep in mind budget is a concern here. I can't just go out and buy vortech pumps or anything like that.