Green Algae and FOWLR

[len58]

I am very new to salt water aquariums. I set up the 75 gallon aquarium 2 months ago. I have slowly added the following:

Royal Dottyback
Scissortail goby
2 clowns
5 blue/green chromis
6 crabs
12 snails

I have good water properties. I test for pH, ammonia, nitrite and nitrates. All good. The fish are all fine. I do 10 gallon water changes once a week. I have the following filters:

404 Fluval - 2 carbon, 2 ??, 4 bio-max chambers
Red Sea Prism protein skimmer

I am constantly battleing green algae. It has overgrown two of the large live rocks. Also, I always have algae on the glass. It does not seem to matter how much I clean it.

Do I have too many fish?

Can I do something to control the algae?

Thanks in advance for any advice.

[leebca]

The quantity of livestock is fine (I'm happy to say -- don't get a chance to say this very often!).

The way to reduce algae is to starve it and then to get your cleanup crew to eat the rest.

You need many many more snails that are herbivores. (I would get rid of the crabs).

But put the snails in after a thorough cleaning AND after you've taken further steps (below).

Since algae needs light, nitrates, phosphates, organics, and trace elements, review how these things may be finding their way into your system.

Fish foods should be low in phosphates with low nitrates. Rinse foods to remove the juicy excess.

Increase water change size to better export these things. I would suggest changing your maintenance to doing a 25% (or more) water change very two weeks.

Verify skimmer is properly sized (don't believe what the manufacturer claims -- actually do this yourself by reading this: What is Water Quality).

Do you have enough carbon on the system? This you have to determine. See above link for water quality issues in general.

With regards to lighting -- fish don't need it. So choose lighting that is good to show off your fish, but doesn't encourage algae. Unfortunately, this may be nearly impossible. Algae can be found in all levels of lighting. However, you can reduce the overall length of the lit cycle.

The above will be your best start. Secondary phase is to introduce nitrate and phosphate absorbing chemical filters to the system if the above doesn't work well enough.

In general, some algae will grow, but the clean up crew should keep up with a minimal growth. You'll still need to do scraping and cleaning, but it shouldn't be because of a large amount of algal growth.