How do I get my balance back?

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A reader worries about the algae in his tank using up nutrients. Jeremy Gay advises.

My tank has been running for six months now. My nitrate and phosphate levels have bottomed out and I’m now getting dinoflagellates. From what I understand, even though my tests are reading zero, the algae is using up all the nutrients, giving it a false impression of what the true levels are. Is there anything you can suggest to help me get the balance back?

My tank is run on the Triton method, so I am not doing water changes; I have a large refugium and then dose elements as needed.

ZAK HARRISON, VIA EMAIL

Jeremy says: There is a lot more public knowledge now about dinoflagellates, cyanobacteria, and diatoms, but at the same time, there have been huge leaps and bounds into researching the microbiome (as well as the lack of it) in newly established reef aquariums. 

Algae and bacteria are incredibly hardy and many ‘nuisance algae’ actually thrive in water with no traces of nitrate or phosphate, and I’ve even had algae grow in RO water. 

Ammonia can be a food source for algae but the cause of it may be down to insufficient good bacteria strains in the system, and we’re not talking about nitrifying bacteria for once.

I would look to seed the system with some mature live rock, some sand from a very mature system, maybe someone else’s macroalgae to add to your own and maybe some wild zoa rocks or soft corals that have come in on mature rock bases. 

I’d also add copepods to help scavenge, along with small hermit crabs, snails and a sea urchin, all of which will combine to graze and hopefully outcompete the dinos — Sailfin mollies are good for this as well. 

The true Triton method uses natural seawater, so if you haven’t used any, try it — but only if it hasn’t been exposed to UV. Natural seawater has been proven to contain strains of beneficial bacteria not present in new reef tanks. Some can even help combat fish diseases! Regarding the nitrate and phosphate, I would use Granular Ferric Oxide (GFO) in a reactor to keep the phosphates and silicates very low, but I would consider adding nitrate, like that from Reef Zlements, to bring nitrate up to 10ppm. A nitrate level may also help fight off the very opportunist dinoflagellates.