Algae only appears when running pumps

Hi, I have a peculiar problem with my pool. I have what looks like dark brown or black algae that hovers in streaks on the bottom of my salt water pool. It only appears when I run my pumps. If I turn off the pumps and brush the pool the algae disappears and will not reappear until I run my pumps for an hour or more. I have an above ground pool that holds 5106 gallons. I use 2 1500gph filter pumps and a salt water system. I recently treated the pool with AngryEgg Algaecide that is suppose to treat green, black, and mustered algae. I followed the directions exactly and not sure what to do now. Initially it seemed to be working and the algae was not as bad but now, 3 days later, it's back to the way it always has been.
FC 4
PH 7.4
ALK 140
Cal 200
CYA 100
Salt 3100

1. Run your pump 24/7. You've added a bunch of copper, and you've got to hope it will precipitate out on the filter.

2. Read the "Best Guess" page. If your CYA level is really 100, you need to understand the Cl/CYA relationship => http://pool9.net/cl-cya/

3. Tell us how you are testing. "Guess-strips" have gotten somewhat better, but they are still really terrible at measuring CYA.

4. Tell us what sort of pool (make/model/size) and filters (make/model) you have. If they are soft side pools, look through the soft-side pool recipe page, for the filter info. If you have Intex or Summer Escapes cartridge filters, you WILL need better cartridges: http://pool9.net/ssr/

5. Do NOT add any more over-priced copper algaecides -- like Angry Egg. Doing so will just make things harder.

One more bit: tell us if you have a copper / salt system: most Intex salt system include copper. If you DO have copper, remove the electrical leads to the copper side of things.

Best wishes.