Time for the cleanup crew?

Ok, so in my 40g tank I've been doing steady water changes of about 5g daily for the last couple weeks. Today my pH is somewhere between 8.0 and 8.2 (hard to tell against the test kit color card) and amonia appears to be at 0. Anyway, the brown algae seems to be dissapearing off the sand bed a bit and the green is encroaching. I'm trying to figure out if it's about time to be ordering my cleanup crew. Can anybody tell me if it's time?

Also, do I need to keep doing these water changes daily? What're the parameters at this point?

I'm not sure about nitrites and nitrates yet. I'll have to test for those when I get home. Thanks for the info though. Now I have something to check against.

I tested my water today when I got home and here were my results:

Nitrites - 0
Nitrates - 10
Amonia - 0
pH - between 8.0 and 8.2

The amonia and nitrites were very easy to see color differences whereas it was a little tougher to pinpoint nitrates and pH. I know the nitrates weren't above 10 though.