removing nitrates from algae use without impacting corals

[nzkiwi80]

I’m testing almost 0 with a Hama tester for nitrates so my topic sounds crazy, but it’s testing zero as I have algae using it.

I’m sure the 101 of removing nitrates is waster change after water change but I don’t want to deplete the system as my corals need it.

So how can I remove nitrates so my algae struggles and dies but still leave enough for my corals

Other elements that algae consume is also low such as iodine.

I have a 350L system and do 25L weekly water changes

 

[mcarroll]

I’m testing almost 0 with a Hama tester for nitrates so my topic sounds crazy, but it’s testing zero as I have algae using it.

I’m sure the 101 of removing nitrates is waster change after water change but I don’t want to deplete the system as my corals need it.

So how can I remove nitrates so my algae struggles and dies but still leave enough for my corals

Other elements that algae consume is also low such as iodine.

I have a 350L system and do 25L weekly water changes

It would take a magic wand since algae doesn't really work that way.

What is your current PO4 level?

Without some nutrients (N&P) in the water, little-or-nothing will be able to grow in and replace the pest algae.

Your cleanup crew will not eat algae that has been allowed to grow to maturity.

This leaves removal up to you – cleanup crew member #1.

Manually remove every scrap of algae. If the algae is very bad, work in small zones like 2"x2" so you can really focus and get every scrap then move to the next area.

How many herbivore snails are in your cleanup crew? There's a decent chance you'll need more....sometimes folks have almost nothing but scavengers in their CUC....or almost no CUC at all.

Iodine doesn't survive long in a reef environment....low readings are normal, even in nice reef tanks.

Investigate with the siphon to see if your rock and sand bed need to be cleaned. If they do, make sure you don't bottom out nutrient levels in the process....either dose your new saltwater with NO3 (≥5ppm) and PO4 (≥0.10 ppm) or siphon into a filter sock (5µ would be ideal) and put the clean water back in the tank. IMO in the short term, dosing some nutrients would be better, if possible.

 

[nzkiwi80]

When i siphon water some patches can be dirty but often is reasonably clean.

I went away for 4 weeks without water changes, no increase in nitrate. Hana readings are almost none so likely a false reading as it’s being consumed by algae.

I’ve also tried increasing feeding but nitrates don’t increase.

I’d get more corals going to try outcompete algae but worried they won’t survive or will be starved

 

[mcarroll]

When i siphon water some patches can be dirty but often is reasonably clean.

That's a good sign. Using a powerhead in your hand to blast detritus off the rocks and out of the sand is another strategy that can be faster if there isn't a ton to be removed. (Siphoning is better if there's a lot.)

I went away for 4 weeks without water changes, no increase in nitrate. Hana readings are almost none so likely a false reading as it’s being consumed by algae.

I’ve also tried increasing feeding but nitrates don’t increase.

I’d get more corals going to try outcompete algae but worried they won’t survive or will be starved

There's no such thing as a false reading...unless your test kit is broken or you're doing the test wrong.

Reading zeroes means there are no nutrients detectable in the water. This is important (not false).

The reason nutrients are important isn't to lower them and kill the algae (which doesn't work anyway), it's to make sure nutrients are present enough to *grow everything else*.

So whether algae are using the nutrients up or the nutrients are being teleported out of the tank by aliens is secondary – the test result is accurate and actionable. ;)

However, you aren't growing an algae farm, so removing the algae is the next most important point. You'll see how much dissolved nutrients there are when the algae are gone.

If the algae has grown out (ie you can see it, it waves in the water, etc) then it's too grown for your cleanup crew so YOU have to remove it by hand now. (Use a technique like I described if there's a lot of algae.)

Adding corals will be an excellent third step, but wait until you've cleared out most of the algae (at least) before adding any.

(BTW, if you already had corals the short term plan would include dosing NO3 and PO4 to stop any damage being done to them.)