Does microalgae disguise Nitrate levels?

[mell0w]

I have a 55 gallon tank with 80~+ lbs of rock. I have green bushy-like algae growing on the back glass in parts that aren't quite visible (behind the rock). I chose to leave it there for nitrate reduction. I also have some on the back parts of rocks (again out of sight) and I use a tooth brush to squash anything ugly that pops up in clear sight. I do weekly to bi-weekly 10gallon water changes (roughly 20%).

It's been a good 2 and a half weeks of no water change so far, and my Nitrate reading is below 5 (API so that's as low as it reads).

I have 2 clown fish and like 15 various snails/crabs/etc and I feed pellets twice a day. Sometimes I feed frozen LRS Reef Frenzy but it seems when I do I get huge algae outbreaks, while my Nitrate test remains 0-5.

I have no sump, no protein skimmer, no reactor. Just a large HOB filter with Phosguard, ChemiPure Blue, and 'nitrogen reducing filter pads'. I used to run polyfil as well and changed it every week but I've stopped.

Anyway, from what I've been doing so far I've never seen nitrates ever be high.

If I were to get a protein skimmer, would that "out compete" the algae / starve it off so I wouldn't have to worry about it as much? Is all the algae just feeding off of whatever nitrate they can find and growing and that's why I can never get a solid reading?

I'm just trying to convince myself I need a new piece of equipment for my tank, really

 

[Kris 2020]

If I were to get a protein skimmer, would that "out compete" the algae / starve it off so I wouldn't have to worry about it as much?
Maybe, but not for certain. I have a protein skimmer and run biopellets and I can still grow chaeto and get some hair algae in my sump.
Is all the algae just feeding off of whatever nitrate they can find and growing and that's why I can never get a solid reading?
Yes, your nitrates read low because the algae is using it to grow, drawing the nitrates out of the water. So it’s not really a false reading.

What is your light cycle like?

 

[Aqua Man]

It is said that algae can mask the true reading of nutrients in the water column. Not sure I’ve actually witnessed this myself.
Nitrates can be processed in sand and rocks also. 2 fish is is low bio load, IMO. Which is helping keep N low
Have you taken a sample to LFS to verify your reading?
Nutrients + light = alga It’s inevitable

 

[mell0w]

If I were to get a protein skimmer, would that "out compete" the algae / starve it off so I wouldn't have to worry about it as much?
Maybe, but not for certain. I have a protein skimmer and run biopellets and I can still grow chaeto and get some hair algae in my sump.
Is all the algae just feeding off of whatever nitrate they can find and growing and that's why I can never get a solid reading?
Yes, your nitrates read low because the algae is using it to grow, drawing the nitrates out of the water. So it’s not really a false reading.

What is your light cycle like?

Chinese black box, at 7:30 am I put it on mid blues, ramp it up on lunch at 11-12 ish to blue 100% and a little white channel (makes it looks more purpley). At 5 or so I ramp down to just mid to low blues. When it's dark out I completely shut it off. So like 10-12 hours of varying lighting

 

[Kris 2020]

Chinese black box, at 7:30 am I put it on mid blues, ramp it up on lunch at 11-12 ish to blue 100% and a little white channel (makes it looks more purpley). At 5 or so I ramp down to just mid to low blues. When it's dark out I completely shut it off. So like 10-12 hours of varying lighting

You may want to consider cutting that down to 7-8 total hours a day and see if your clean up crew can catch up with the algae. You could also pick off what you can by hand and go lights out for a week or so if you don’t have coral or nems.