Algae Scrubber and dosing Nitrates

[Treefer32]

This is spawned by an experiment I was doing and I'm reaching a definitive conclusion. I run an Algae Turf Scrubber from Turbo Aquatics on my 350 gallon very lightly populated mixed reef.

I had a massive fish die off lost 15 out of 19 fish due to heater (whole other issue) but important to note that my scrubber went nuts. It was full every 3 days after the fish die off.

Fast forward now to 3 months after the aftermath. I have 3 fish left, and they're doing very well. Eating well, active, and not stressed at all. I've been testing phosphates and nitrates with red sea pro test kits. Nitrates are undetectable now. However, phosphates a month ago were .12. Higher than I'd like. I had visible algae in the display still. I hand pulled alot of it and it didn't grow back. The scrubber was slowing down significantly. It was starting to go back to the slime algae stage, no longer growing the thick hair algae it had been growing.

I wondered, what's the issue? I did some reading that for algae to grow there needs to be a ratio of nitrates and phosphates. With nothing left to produce nitrates, my nitrates depleted much faster than phosphates. The last time I cleaned my scrubber screen was a week ago. I decided, to apply some brightwell's aquatics nitrates to the scrubber. I did 16 ml. 8 ml with a dropper on each side of the screen, making sure most of the screen was covered.

I restarted the scrubber and waited. Today I checked it (5 days later) There was so much algae on the screen that it was nearly plugging the emergency drain. The water line in the scrubber box was nearly to the top. I pulled the screen out and cleaned it, and I had a larger ball of algae than when I had the fish die. I had tested phosphates a couple days ago and they had dropped from .12 to .08.

My understanding is I want them around .04 - .06 to keep most corals happy.

So, I dosed another 15 ml of nitrates to the screen again today. I just wanted to note that learning the balance between nitrates and phosphates is going to make my turf scrubber all the more powerful going forward to manage algae and water cleanliness.

 

[Ron Reefman]

This is an interesting idea. I wonder if anybody else can confirm or refute your conclusions. I can's say as I don't have an ATS, I do harvest a gallon or more of macro algae from my refugium every couple of months, or whenever I see any algae in the DT. But I haven't tested for nitrates or phosphates except for a year ago when I did have a bit of an algae issue in the DT and the refugium was just getting set up.

 

[Reefer1978]

My frag tank only has 3 tiny fish in it. I dose both Nitrates and Phosphates as needed, confirmed by weekly Red Sea test, I am about to go test my water now. Scrubber works and grows algae pretty steadily.

You don't need to dose nitrates onto the screen. I just down them right into my sump as coral need them also.

 

[Treefer32]

Good point on dosing them to the sump vs. screen. I figured the water falling over the screen would gradually move them into the water column. I can tell something changed as algae is growing on the glass faster now. I have slime algae on the display glass in hours in stead of a day or two. So, it's definitely getting into the water column and fueling algae growth. Glad I'm only doing 16 ml in a 300 gallon system. A local fish maintenance person said I'd have algae growing everywhere if I dose too much. So, staying at the half of what the bottle says to dose for 300 gallons of water volume.

 

[Reefer1978]

My Po4 is .12 and No3 is 30 ppm. I do not have algae everywhere but I do have to clean the glass few times a week. Scrubber should be able to keep up and outcompete algae in the DT.