phosphates not to blame ?

[binford4000]

It has been my experience that Po4 is a major contributor but not the only one. Over extended light cycles as well as natural sunlight can also add to the problem. Po4 in measurable levels with a hobby test kit is sign of poor water quality that of course allows nuisance algaes to grow and propagate. With that said lets talk about the testing. Our standard test kits are very basic and easily contaminated . Which will result in poor or incorrect readings. Many of the kits will not even produce the same results with the same water sample twice in a row. They are intended to be accurate enough to help you maintain a healthy aquarium but can also do the opposite. If you are able to keep macro algae alive you have traces of Po4 and No3. This is not a bad thing. Corals do need small traces of both. Even when most reefers pound their chest and claim they have absolute zero results their is really still traces of them. True zero results will starve out and kill any macro you put in your system and a turf algae filter would probably never grow algae. With that said it has been my experience if your results from testing are good then flow would be your next place to trouble shoot. Many people think of flow in volume or how hard the water in GPH is being moved. While high turnover rates are a good thing within reason the quality of the flow is more important. Good flow will first have enough force to circulate the complete enclosure with no dead spots. Good flow also suspendeds and help remove waste and uneaten foods off the bottom and rock scrapes so it can be removed by via an overflow,filter or HOB skimmer. If that is not the issue then setting up a good clean up crew based on your tanks issues is next. But really if your keeping coral natural cleaners should have already been part of your planning. Another thing to consider,and this an after thought is pay attention to Mag levels. Not only will it keep your calcium and alk from bonding it also naturally helps reduce.algae.

Algae scrubbers do work but require a lot of time and constant cleaning and really don't reduce excesses nutrients in that large of a volume. They quickly become a big PITA! Unless your someone who enjoys working on your tank all the time. Better results can be accomplished easily with bio pellet's,nitrate reactors,larger water changes,Zeovit also has very good reducing products.that work well. Many reefers use Vodka or some other carbon source. A top of the line protein skimmer is also an excellent addition. I personally use Pobido's Bio Digest and Brite wells reef bio fuel for a safe carbon dose and maintain a mag level of 1600 ppm. I can now kill any type of algae in a matter of days! Cheato turns white in less the two days . Good luck and man was that a long .02. Lol