As for the algae, what kind is it, where is it growing, and please explain "grows fast"? Does fast mean an inch a day or more?
Here is a standard post for algae or cyno control and elimination.
1. If you already use RO
water, test your source water. You may need to
add a deionizer to it. This is the most important step.
2. Siphon as much of it as you can. Breaking it up only helps it to
spread. You need to do this as frequently as possible.
3. Review your feeding habit. Are you overfeeding? Do the fish eat what
you put in at feeding time within a few minutes, or is there food lying
around the bottom after? Also, if you use frozen, make sure to drain
the as much of the packing juice as you can before adding.
4. Do you have adequate water movement? Any dead spaces in the tank?
5.Do you have a skimmer? If so, is it producing daily amount of dark
Are you running GFO
? You can also run a PO4
sponge which will help, but you need to address the other underlying causes.