High Nitrates in fresh saltwater!!

phoenix001

phoenix001

Premium Member
Recently I started noticing green hair algae growing on the rocks and despite weekly water changes, running GFO, Carbon and starting a refugium, the algae is getting worse. Salifert phosphate test shows 0 but salifert nitrate test is close to 100ppm - so I have a nitrate problem for sure. All of my top off and new saltwater is RO/DI and TDS is 0 - when it reaches 1 I replace my resin immediately. I have a 140 cube with a YT, pair of clowns, lunar wrasse, valentini puffer, coral beauty and a pair of diamond gobys. I feed every couple of days typically pellet, some nori on off day's and then a cube of Mysis once a week. So, I don't see that I am adding an abundance of nutrients. Skimmer is a bit undersized for the tank - bubble magus 5 curve if you include the 35 gallons in the sump. The very interesting part of this story is that I also tested my newly made saltwater and found that it was as high as the tank water, so my new saltwater appears to be the source of my problem, but how?

I tested my ro/di water by itself with the same salifert test kit and result is 0 nitrates. I went ahead and replaced the sediment and carbon filters and I will tell you that the sediment filter was disgustingly brown as well as the first carbon filter, but not the second carbon (I run 1 sediment and 2 carbon). I use Instant Ocean mix for my weekly water changes. The pump I use to mix the water is a mag 7.5. I have noticed a brown film coating the bottom of the Brute can that I use and it also coats the pump. I have cleaned out the brute and pump a few times as a result of this brown stuff the most recent time right before my last water change this past Sunday yet I took a sample of the saltwater in the brute this morning and it is high in nitrates.

Could the problem be the IO mix or am missing something to check?

Thank in advance
 
The brown film is residue from instant ocean. I get that all the time reason i switch to another salt. Hated that crud and constant cleaning of the container.


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Take a sample of makeup water and tank water to your LFS for a second opinion.

I'd bet the farm that you don't have 100ppm nitrates in your makeup water.
 
I'm not sure if a saltwater nitrate test kit can be used on freshwater.. I believe so but not certain...

It could be your RO/DI water but unlikely..
Its possible that your salt mix is the problem.. (I believe I have seen users report that before)
Its also possible that you are seeing a testing error..

You need to make a batch of new saltwater (outside of the brute) and get a second opinion on the nitrate levels..

Let us know what you find out..
 
Ok, I am going to mix up a new batch of saltwater in a 5 gallon bucket using the same IO - will post the results
 
BTW the brown stuff is supposedly an anti-caking agent added in the IO salt that is normal/harmless but can be annoying
 
Yeah it gets all over the sides of the brute and all over the pump as well. Maybe a dumb question, but any chance the Brute itself or the MAg 7.5 is the problem?
 
I think most nitrate kits will work on saltwater or fresh water, but I'm not 100% sure. I doubt that any nitrate could be coming from the RO/DI if the TDS meter is accurate, so I suspect your measurement there is correct, even if by accident. There might be some nitrate in the salt mix, but I suspect that the problem is in the tank. Have you tested for nitrite recently? Nitrite will interfere with nitrate test kits, although that problem is very rare.

Even with low nutrient input, a buildup of debris in a coarse substrate, for example, can lead to a higher nitrate level. Better skimming might help, too.
 
Thanks for the input but why would my freshly made saltwater return such a high nitrate reading? Maybe a mistake - will test new saltwater very soon. Also did not test nitrite so will do that as well
 
I think Bertoni misunderstood and didn't catch on to the fact that your newly made saltwater (not added to the tank yet) is reading high in nitrate..
 
I thought that the 100 ppm was from the tank? 100 ppm in the fresh water itself sounds like a measurement probably, possibly a lot of nitrite interference, or a very bad batch of salt.
 
Last edited:
Well no nitrate in the saltwater I mixed in the 5 gallon bucket. At a Lose for the moment - guess I will mix up my saltwater in the brute as I would normally and then take a reading
 
phoenix001 said:
Well no nitrate in the saltwater I mixed in the 5 gallon bucket. At a Lose for the moment - guess I will mix up my saltwater in the brute as I would normally and then take a reading
Click to expand...

I'm going to guess your mag pump might be split and messing with your results.

Speaking of results have you duplicated the results several times?
 
I don't know of any way a pump could release nitrate. Nitrate is an end result of protein metabolism. I suspect the problem is in the tank.
 
Well, zero nitrates in my new batch of freshly made saltwater. Either I was mistaken in my first test or replacing the sediment and carbon filters in my RO/DI was the fix as that is the only action I took.
 
You could test your tap water, but it should be well below 10 ppm nitrate, as that's the safe water drinking limit, if my memory is correct. How high was the number from the freshly-mixed saltwater?
 
Well, the mystery continues. The picture you see here is a Nitrate test against the remaining fresh saltwater from my water change yesterday. The same water I tested yesterday for my water change had no detectable nitrate and this morning it does - I tested it twice. What could of happened between yesterday morning and this morning?

Jonathan - I did test my tap water and it looked to be between 10-25ppm. Tested my RO/DI water and as expected there was no detectable nitrate.

I added a picture of my water changing brute. Again, I am using a mag 7.5 and my routine is very simple - Fill up the brute with RO/DI typically overnight, once full I plug in the heater you see in the pic, once the water is at 79-80 degrees, I add the IO salt mix to 1.024. I do this a day or 2 before I conduct my water change. Again, what you see in the brute pic is what I typically have remaining post water change. I have approximately 173 gallons of total water volume and my water change is around 19% weekly.

Maybe I should replace the brute, the pump or both - very strange

picture.php


picture.php
 
I am not sure what happened, but the pump and the Brute should fine with a bit of cleaning, at most. I am not sure what might interfere with a nitrate kit, but something must be entering the water. I just don't know exactly what or how. Was the container kept covered?
 
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