Nitrate and algae question

[Cherie cook]

Here’s a question I’ve never gotten a good answer for..I have lots of nuisance algae in my tank, bubble, ulva and hair algae..but my nitrate will still measure on the low side most of the time. Measures anywhere from 0 to 4 via Hanna checker. I sometimes supplement with neonitro because I’m scared to let it drop to 0..but I’m wondering if the presence of all this nuisance algae means there’s enough nitrate in the water column to support my corals despite the low readings? Like is it being taken up by the algae so it’s not measurable?

 

[TX_REEF]

Yes, likely being taken up by the algae growth. unsurprisingly, cleaning up algae tends to not just make your tank look nicer, but also enhance coral growth since less nutrients are being taken up by the algae. I see this very directly in my frag system especially.

 

[CHSUB]

A HR Hanna checker doesn’t have the resolution to read low no3. So you likely don’t have “low” no3 compared to even polluted ocean waters.

 

[Mr. Mojo Rising]

Algae consumes nitrates so it skews the test results, more so the worse the algae is. And feeding things like neonitro when you have a bad algae problem just feeds the algae. Your corals always focus on consuming ammonia rather than nitrate, they have to expend energy to break down the nitrate into more useable elements.

 

[Cherie cook]

A HR Hanna checker doesn’t have the resolution to read low no3. So you likely don’t have “low” no3 compared to even polluted ocean waters.

Meaning..what?

 

[Cherie cook]

Algae consumes nitrates so it skews the test results, more so the worse the algae is. And feeding things like neonitro when you have a bad algae problem just feeds the algae. Your corals always focus on consuming ammonia rather than nitrate, they have to expend energy to break down the nitrate into more useable elements.

So feed ammonia rather than nitrate?

 

[TX_REEF]

So feed ammonia rather than nitrate?

do you have fish? if so, you are already feeding your corals ammonia and probably don't need to add anything additional other than what you feed the fish. I'd just focus on cleanup of nuissance algae manually and via CuC.

 

[EnterName]

Meaning..what?

Global average nitrate levels for coral reefs: 0.25μM +/- 0.28μM (Source)
This is roughly between 0.016ppm and 0.033ppm if my math isn't off.

This means what we consider "low nitrate" in the hobby is still insanely high when compared to actual coral reefs and most tests aren't even capable of detecting those levels.

Whether natural coral reef levels or the currently recommended "elevated" levels are preferable is an ongoing debate I won't comment on I personally have seen both approaches work.

 

[CHSUB]

Meaning..what?

Meaning your no3 is not low, just below your hobby test kit resolution. Even a level of 0.5 ppm no3, which is likely below hobby testing resolution, is 500% higher than levels in natural reefs that support algae growth just fine.

 

[Cherie cook]

do you have fish? if so, you are already feeding your corals ammonia and probably don't need to add anything additional other than what you feed the fish. I'd just focus on cleanup of nuissance algae manually and via CuC.

Thank you!

 

[Randy Holmes-Farley Verified Community Expert]

Generally algae acts like any other user of N and P, such as corals. It’s not a false reading, and enough algae may limit nutrients for other users, including corals and other types of algae.

 

[Dan_P]

but I’m wondering if the presence of all this nuisance algae means there’s enough nitrate in the water column to support my corals despite the low readings? Like is it being taken up by the algae so it’s not measurable?

Undetectable nitrate has been described as a nitrate level sufficient for coral growth when the coral are doing well and insufficient when the coral are not doing well, all things being equal. Since detectable nitrate levels seem to pose no harm, the ambiguity around not detectable nitrate is removed by dosing nitrate (or some ammonium salt) to ensure sufficient nitrate.

I don’t know whether flourishing algae necessarily means there is sufficient nitrate (inorganic nitrogen) for coral growth. I would think it is a poor diagnostic tool.