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Gtboosted89
12/28/2017, 11:37 PM
As the titles shows I have pretty high phosphates and undetectable nitrates. Can I add potassium nitrate to combact this?

What product can I order for potassium nitrate and how much should I dose for a 55 gallon total system.

I have about 25 sps frags. All are encrusting but slowly. Good PE on most.

Big E
12/29/2017, 02:37 AM
What type of export system are you using? There are ways to reverse what you have going without dosing nitrate depending on the nutrient export system.

RobZilla04
12/29/2017, 04:44 AM
Are you having algae issues? Are your SPS corals showing signs of being unhappy (low/no polyp extension, color loss, etc.)?

If no to both of those, ignore the test results and shoot for consistency. In battling a non issue you very well may likely create one.

Gtboosted89
12/29/2017, 07:34 AM
For export just a bunch of live rock plus live rock and matrix in media bags in my sump. Weekly 15% water changes and skimmer.

No issues as of yet but wondering if these test results mean that growth is hindered. Dkh has been at a steady 9.5 and I would like to keep it around this value for cushion both ways.

Timfish
12/29/2017, 07:44 AM
+1 to Robzilla04.

FWI you PO4 level is in the range of normal for reef systems in nature. Be very careful about lowering PO4. It's essential for corals and too low really screws up a reef system potentially giving algae the upper hand as it can out compete corals for phosphate. Watch Richard Ross's video (https://www.youtube.com/watch?v=ZRIKW-9d2xI) and look at this paper on the effect of phosphate deficiency on corals (http://www.sciencedirect.com/science/article/pii/S0025326X17301601) grown in aquariums for several years.

Gtboosted89
12/29/2017, 07:53 AM
I also forgot to add that I had planned to have my nitrates around 2-10ppm and it's the reason why I finally decided to test for p and n.

Yesterday I tested to have a baseline and that's when I noticed the ratio was off. Even with no problems, surely it can mean slow growth right?

I do have a small quarter size chaetomorpha ball in the sump. I doubt this can alter the phosphates or nitrates at the moment.

nereefpat
12/29/2017, 08:08 AM
Some folks do dose a little nitrate.

I went through the math a while ago. I think it was about a 1/2 gram of KNO3 to raise 1ppm nitrate in 100 gallons.

RobZilla04
12/29/2017, 08:15 AM
I also forgot to add that I had planned to have my nitrates around 2-10ppm and it's the reason why I finally decided to test for p and n.

Yesterday I tested to have a baseline and that's when I noticed the ratio was off. Even with no problems, surely it can mean slow growth right?

I do have a small quarter size chaetomorpha ball in the sump. I doubt this can alter the phosphates or nitrates at the moment.

I wouldn't suggest shooting for target numbers. Wait until you see growth before adjusting or looking for ways to export beyond the current set up. As already mentioned it can irritate corals, stunt growth, or create new issues altogether.

If the chaeto in sump is surviving/growing, it is absorbing the nutrients and creating a balance. If the chaeto fades, you're low on nutrients which chaeto needs. If not algae, let things be. If you have chaeto growing and algae, then there is quite a bit of excess and it's time to export and look for causes.

Keep a log when you test. <--- best piece of advice I got early on.

bertoni
12/29/2017, 04:12 PM
Personally, I wouldn't worry all that much as long as the corals are doing well. GFO would help reduce the phosphate level, but it might take a lot of media over time, and GFO can be overdone.

Adding nitrate might help reduce the phosphate level, depending on what nutrients are limiting for the system. The tank might need some organic carbon along with the nitrate, but that's hard to predict. You could try dosing sodium nitrate or some other safe nitrate compound to see what happens. Sodium nitrate in food-grade form was available on Amazon. I am not sure what a good source for potassium nitrate might be, but it's generally safe, as well. Sodium nitrate is less likely to shift the ionic balance, but the difference is minimal with a decent water change schedule.