no3 dosing = brown sand?

[bubbaque]

I usually get clear looking through the side of my salifert nitrate test. I decided to dose no3, I guess to chase a number and I see everyone say it shouldn't be zero. Sps colors don't look faded but I do notice my frogspawn is open more when I dose nitrate. The issue I have is when I do dose potassium nitrate, even to 2 ppm my sand turns brown. I do have chaeto in my fuge that grows pretty rapidly, so I do not feel I am nitrate limited.

I do feed pretty heavy 2 - 3 cubes worth of LRF and some pellets per day in my 180 gallon. I have about 20 fish, including 4 decent sized tangs. Should I stop dosing nitrate or just ride out the brown sand and hope it finds a balance and goes away?

 

[Cory]

Theres either silcate in the potassium nitrate or silicate in your water and the diatoms are nitrate limited.

 

[bubbaque]

I do run gfo, I would think that would pull the silicate out.

 

[Cory]

Gfo does but is better at po4 iirc. Aluminum oxide is much better at silicate removal.

Also stirring silica sand will release silicate. Most for reefs are caco3 based but some have silica in it too.

Whats your tds of ro/di?

 

[bubbaque]

I get 2 tds into DI and 0 out.

 

[Cory]

Top is diatoms, bottom is cyanobacteria

Is it for sure diatoms and not cyano?

 

[bubbaque]

Top looks like mine. Mine is just not as bad.

 

[Cory]

Its most likely diatoms as long as it doesnt look like this: dinoflagellates

 

[bubbaque]

It's diatoms but only appears after I dose potassium nitrate. Here's a pic.

 

[Cory]

It's diatoms but only appears after I dose potassium nitrate. Here's a pic.

Must be silicate coming from somewhere then. Just gotta find the source

 

[BluewaterLa]

How old is your system ?
It is normal for reefs to go through all sorts of algae and diatom issues along with bacteria blooms or problems.
We are directing an ecosystem filled with many many different life forms.
Adding anything into the tank or organics breaking down can and will fuel something to grow wether we see it or not with out eyes.

If your tank is new or relatively new, was started sterile and run as a low nutrient system then you may have not gone through the process of tank "uglies" or all of them yet and this could be what you are experiencing by adding nitrate to the system via dosing.
It's normal and if you need to dose it regularly or just a few times to get your nutrients to an acceptable level your tank likes then keep things balanced and stable.
The diatoms will disappear when things like silicate are used up.
Diatoms are actually good for the tank and many fail to accept this fact, they are a good food source for many critters and micro fauna in our tanks.
Most of these critters can survive off of other food sources while others will perish or reduce in population as a result of no diatoms available to eat.

So it's really not an issue or problem but rather normal so as long as there isn't significant source of silicates being added to the tank then this condition is temporary.

Good luck and happy reefing
BluewaterLa / Mike

 

[bubbaque]

Thanks for the info! This 180 gallon tank is an upgrade from a 75 gallon. The 180 has been running for about 5 months now. I took all the rock out of the 75 and put it straight into this tank, I also had rock in my sump from the 75 curing so I hopefully wouldn't run into issues.

The chaeto in my sump will suck any nitrate out of the water. If not for the chaeto I'm sure my nitrates and phosphate would be sky high. I have roughly 20 fish and four of them being tangs. I feed a ton each day, roughly 4 cubes worth of frozen and some pellets.

Coralline is growing all over. I went through the initial diatom phase and sand looked pretty good. I dosed no3 for no reason other than reading it should be detectable. Sps corals are not faded but do notice my frogspawn gets a little bigger if I dose no3.

I dosed no3 and everything turned brown again and started getting what looks like green hair algae on the back glass, but the tangs keep it short. I have to dose daily or it's not detectable on salifert because the chaeto sucks it up.

 

[bubbaque]

Here are better pictures. It's not horrible but it was clean before dosing.

 

[reeferfoxx]

Silica is quickly removed with GFO. That might just be some residual diatoms or the start of cyano. If you deplete PO4 and higher amounts of NO3 you will get unwanted algae. I would remove the GFO and monitor po4 since you are running a refugium. I like my po4 around 0.02 and nitrates around 2-5.

Here is an article about GFO by Dana Riddle. If you scroll down you will notice that 17mg/l of silica can be removed in less than 18 hours.

 

[bubbaque]

I removed the gfo yesterday. After I talked to Mike and Terry, because they have a beautiful tank, on how they run no nitrate and low po4 due to having two skimmers and turf scrubbers. She said just feed a lot and don't worry about nitrate, just keep some po4 in the tank. I'm going to go back to what I was doing since I didn't have any issues but started dosing to just chase a number.

 

[reeferfoxx]

I removed the gfo yesterday. After I talked to Mike and Terry, because they have a beautiful tank, on how they run no nitrate and low po4 due to having two skimmers and turf scrubbers. She said just feed a lot and don't worry about nitrate, just keep some po4 in the tank. I'm going to go back to what I was doing since I didn't have any issues but started dosing to just chase a number.

I always find it weird when people say no nitrate. Because the lack of nitrate would cause issues. The fact that they feed heavily and have fish pooping makes me believe there is nitrate but it's controlled. I suppose my approach is I don't feed heavy and I'm limited to just a skimmer and refug. I also don't feed coral. I just keep noticeable amounts of nutrients in the water column.

 

[bubbaque]

I always find it weird when people say no nitrate. Because the lack of nitrate would cause issues. The fact that they feed heavily and have fish pooping makes me believe there is nitrate but it's controlled. I suppose my approach is I don't feed heavy and I'm limited to just a skimmer and refug. I also don't feed coral. I just keep noticeable amounts of nutrients in the water column.

I think most who say no nitrate don't actually mean NO nitrate. In my case my chaeto still grew like crazy and coralline wouldn't stop spreading and my corals didn't look faded. I know there is nitrate just from having so many fish and the amount I feed. I think people who run into nitrate issues being low are the ones who feed lightly or have low amount of fish.

 

[bubbaque]

Before I decided to go back to not worrying about no detectable nitrate I called reefs direct, world wide corals and top shelf aquatics, since they are so close to me. I asked their opinion on no detectable nitrates and they ALL said don't worry about it. Top shelf told me they can't keep nitrates in their display tank but they "feed a ton".