Very High Nitrates Post Cycle

Faithbleed · Apr 16, 2020

Hi All

I've completed my cycle using One and Only and a combination of shrimp and Ammonia Chloride (long story) on my Reefer 425XL.

The cycle took 4 weeks and it's been over 2 weeks since then.

Fish (a Foxface and Sunbrust Anthias) were added 3 days after the all clear and they're doing well.

Ammonia has consistently read 0 (API, Seachem and Salifert verified), Nitrite has been reading 0.1 and Nitrates have read +100 since since cycle finished (both Salifert).

I'm starting to get a bloom of what I'm assuming is diatoms.

I've been feeding vitamin enriched frozen mysis and brine with a bit of nori/vege clip food now and then. I've been on the heavier side to ensure the Anthias settled in and was getting fed, but I'm winding back now.

It's possible it's an false high reading as there's still minutely detectable nitrite which could be throwing off the nitrate readings, but I'm not sure when or if they will ever read 0, so that's hard to verify. From memory very low levels of Nitrite are somewhat common early on?

I've done 2x 30% water changes, but Nitrates haven't dropped it below 100 yet and I can't produce more than 40% water change water at one time to do anything larger.

I'm going mostly with the Aquaforest method for this tank, so I'm considering starting Pro Bio S and -NP Pro to assist with bringing Nitrates down. I also also have a bucket of Phos Minus and Zeo Mix ready to use if required. I'm currently running carbon in a reactor, but nothing else apart from filter socks and skimmer for filtration.

I've got no corals yet and lights are only on about 10% for 9 hrs, but I really want to bring my water in line before I add anything else.

I have space in my sump to run a fuge, but don't have a light or chaeto yet and won't be able to get them for a while yet due to lockdown where I am, but it is my intention long term to run a fuge.

Given my situation, can anyone offer any advice to reduce Nitrates?

brandon429 · Apr 16, 2020

Your feed and bioload will keep nitrates from being low, they’ll compound over time and increase as detritus starts to build up since this tank isn’t selecting for low nitrates.

have no sandbed if you want max nitrate control (they catch and hold waste for most tanks, and produce nitrate vs reduce it)

Randy likes using simple vodka dosing and skimming to work his nitrates / read from chem forum posts. His article on nitrate in the reef tank says water changes won’t help / has to hit the source

Rmckoy · Apr 16, 2020

Being a newer setup .
the first initial water change should be a large 50% or more knowing nitrates will be excessively high .

depending on your water source .
if it’s RODI and with 0ppm nitrates it will take a little
Time to lower nitrates but it is possible
If you’re changing 30% water . The best possible is a 30% reduction in nutrients .

slow down on feeding and increase water changes and see how that works .

homer1475 · Apr 16, 2020

At the end of your cycle(when nitrates are high), you should have done the largest water change possible(even 100% is ok and recommended).

I would do the largest water change possible for you. Just match parameters, Alk, CAL, MAG, temp, and salinity.

Plecosam · Apr 17, 2020

Your cycle is exhibiting the same signs as my cycle, what test kids are you using?

My tank was testing nitrates well over 100ppm, this high reading with minute traces of nitrite. Let us say for argument nitrate was 100ppm, really hard to tell but I think the Salifert kit was reading much higher. So going with with 100ppm nitrates, some said excess decaying matter, but I completed a 25% water change and thus nitrates should be around 75ppm. Well no, the tank still tested very high, off the scale high.

I gave up testing nitrates until nitites were undetectable, once undetectable I completed another 25% water change and nitrates read between 5 and 10ppm. No way near the 50ppm they should have been if decaying matter was the problem and my nitrate kit was testing correctly.

Faithbleed · Apr 17, 2020

Plecosam said:
Your cycle is exhibiting the same signs as my cycle, what test kids are you using?

My tank was testing nitrates well over 100ppm, this high reading with minute traces of nitrite. Let us say for argument nitrate was 100ppm, really hard to tell but I think the Salifert kit was reading much higher. So going with with 100ppm nitrates, some said excess decaying matter, but I completed a 25% water change and thus nitrates should be around 75ppm. Well no, the tank still tested very high, off the scale high.

I gave up testing nitrates until nitites were undetectable, once undetectable I completed another 25% water change and nitrates read between 5 and 10ppm. No way near the 50ppm they should have been if decaying matter was the problem and my nitrate kit was testing correctly.

Thanks for your response Plecosam.

I'm using Salifert for Nitrite and Nitrate - I've had mixed experiences with them in the past, but they're better than the API ones I've also used previously. I'm likely going to pickup some Aquaforest ones for the future.

I read that current Nitrate test kits actually test Nitrite in some form to give a total Nitrate result. Detectable Nitrite can put the Nitrate test out by 10x to 100x more than it should be, so I'm inclined to believe that this is a false high reading more than anything.

I started with dry rock that I bleached (and Seachem Primed), so there was virtually zero decaying matter in the tank. There was a shrimp in there for 2 weeks, but that got taken out and replaced with Ammonia dosing for the other 2 weeks.

It's good to hear that someone else has experience the same thing.

How long did it take for your Nitrites to become undetectable?

Thanks everyone else for the advice, I'm going to continue to do water changes weekly in the hopes of making a difference on that front.

Plecosam · Apr 17, 2020

Nitrites took around 2 1/2 weeks they sat on the lowest colour of the API scale for 2 weeks, then trace amounts for 3 or 4 days. No idea of the true numbers but detectable with the kit.

Faithbleed · Apr 19, 2020

Just thought I'd give an update to this. I tested today and Nitrites finally read 0. Nitrates are now 10% what they were reading. Nitrates are now between 5-10, so that's a relief. It's consistent with the theory that detectable Nitrites interferes with Nitrate testing/readings as well as Plecosam's observations that Nitrites drop off completely around 2-3 weeks after the cycles completed. Thanks again for all the advice guys, consider this one solved.