Help with algae

I have been having issues with algae in my tank lately. Here are some stats on the tank.
40breeder reef w/ 20 gallon sump
Rapid led lights
Water changes done biweekly.
Here are some pics of the algae
It is a brown color and is stringy. It is growing on all of my rocks and on some corals. I occasionally remove it with a toothbrush but it is persistent. Please help.

 

The algae is sometimes purple

 

Sounds like Cyanobacteria.

Do you have enough flow?

RO/DI water only?

Have you tried using any GFO?

 

+1. You could also try feeding less and decreasing the number of hours your lights are on per day. A skimmer would also help (if you don't already have one).

 

I do have a skimmer. It may be the flow. And I am not running any GFO currently. How easy would it be to start rubbing GFO. And what is GFO

 

GFO is granular ferric oxide. It removes phosphate in the aquarium. Phosphate feeds algae. It is generally tumbled in a media reactor.

Are you using RO/DI water?

 

Yes I only use RODI water in my tank. What could be the source of these phosphates

 

Food adds phosphates.

I would blow all the rock and corals off daily and then clean the mechanical filtration.

Increase flow especially to those areas with the most algae growth.

Next I would check pH and Magnesium levels, I tend to develop more cyanbacteria and algae problems when those values are low.

You can buy phosban or GFO without having to use a reactor.

Move to ------ Algae.

 

I will start cleaning daily. Most all food that I feed is consumed immediately. How can I run GFO without a reactor?

 

IMO a reactor would be a great investment. GFO is not cheap stuff, and you will get a lot more use out of the GFO by tumbling it in a reactor. Thus, in the long run, it will probably be cheaper to just invest in a reactor from the beginning.

I believe some people may run GFO in media bags. However, you would want to make sure the GFO is constantly tumbling or else it will basically clump together like a rock and be useless