Carbon dosing for 1 1/2 weeks, no sign of nitrate reduction (skimming wet).

[2Wheelsonly]

I have a mature SPS reef (300G) and my nitrates have hit 25ish. Even with very light feeding (LRS reef frozen) once daily I can't seem to get them down.

Before carbon dosing I had to dos po4 as I was showing 0-1ppb (0.003) on my hanna ULR checker. My fish load isn't huge for the size tank I have but they are getting big (3 yellow tang, 1 sailfin, 1 hippo, 1 powder blue and 2 wrasse).

My corals are getting pale which is odd as I have kept my po4 via daily dosing at a consistent (11ppb) 0.03 and my nitrates are stuck at 25. I have used 3 nitrate test kits and also tested my kits against the water from purchased frags. I am using a ton of light so that may be the reason for light colors...

I started out with 35ml of nopox and switched to vinegar after three days. My daily dose of vinegar is 80ml and it has not put a dent on my nitrates. My skimming has become a pain because it's either super dark and thick and overnight goes wet and overflows (preventing export). Recently I have been just checking my skimmer cup every 3 hours and basically taking out 8 cups of light colored skim daily.

At what point should I see nitrate reduction? I just want to get down to 5-10 but it's not budging!

 

[Randy Holmes-Farley]

It can take a while to see reductions (longer than you have dosed), but it is also possible one or both of your measurements is off.

 

[Bramzor]

If you where dosing PO4 before dosing carbon because it was too low, and now started to dose carbon to lower NO3, it might be that bacteria has no access to PO4 which will stop them from using NO3.
When you do not see any effect of dosing carbon, you should not increase it as it will only lower PH and lower KH which is probably not what you want.

 

[2Wheelsonly]

It can take a while to see reductions (longer than you have dosed), but it is also possible one or both of your measurements is off.

You think this could be the case if I get the same results with 3 different brands of no3 tests? (NYOS, Salifert, API) my hanna is fairly close to my ICP test results (ICP said I had 0.03 po4 while hanna ULR thought I had 0.01)

If you where dosing PO4 before dosing carbon because it was too low, and now started to dose carbon to lower NO3, it might be that bacteria has no access to PO4 which will stop them from using NO3.
When you do not see any effect of dosing carbon, you should not increase it as it will only lower PH and lower KH which is probably not what you want.

Is there any way to tell if the po4 showing up on my test is actually available? I read this as some systems can't be carbon dosed? Keep going or stop the dose?

Thanks for both the responses btw!

 

[Randy Holmes-Farley]

Is there any way to tell if the po4 showing up on my test is actually available? I read this as some systems can't be carbon dosed? Keep going or stop the dose?

If you detect phosphate with a test kit, it is available.

 

[Randy Holmes-Farley]

You think this could be the case if I get the same results with 3 different brands of no3 tests? (NYOS, Salifert, API) my hanna is fairly close to my ICP test results (ICP said I had 0.03 po4 while hanna ULR thought I had 0.01)



Is there any way to tell if the po4 showing up on my test is actually available? I read this as some systems can't be carbon dosed? Keep going or stop the dose?

Thanks for both the responses btw!

Could be. Lots of folks here confirm incorrect readings. lol

Not the most likely, however.

 

[2Wheelsonly]

It's crazy to me that my nitrates are so high. Colors are on the pale side, esp with my LPS sitting in the sand bed. Not a single spec of algae to be found in the tank, even my return jets are clean. Glass needs to be cleaned weekly and it seems more like a white smear than algae. Water looks crystal clear and I now have my po4 stable at 0.06 without dosing; keeping eye on it and continuing to carbon dose daily. Will give it 1 more month before I just assume my tank is immune to carbon dosing.

I will probably throw these test kits in the trash and stop testing nutrients all together, I am starting to feel that it's a useless task. I will just look at the corals and assume pale = hungry and brown = too much and if the test kits think I have 100+ nitrates then I guess i'll have 100+ nitrates and keep doing my thing.

 

[Randy Holmes-Farley]

It's crazy to me that my nitrates are so high. Colors are on the pale side, esp with my LPS sitting in the sand bed. Not a single spec of algae to be found in the tank, even my return jets are clean. Glass needs to be cleaned weekly and it seems more like a white smear than algae. Water looks crystal clear and I now have my po4 stable at 0.06 without dosing; keeping eye on it and continuing to carbon dose daily. Will give it 1 more month before I just assume my tank is immune to carbon dosing.

I will probably throw these test kits in the trash and stop testing nutrients all together, I am starting to feel that it's a useless task. I will just look at the corals and assume pale = hungry and brown = too much and if the test kits think I have 100+ nitrates then I guess i'll have 100+ nitrates and keep doing my thing.

High nitrate does not necessarily mean a lot of algae. Algae needs "enough" of many things, and having more of one doesn't make it grow faster.

 

[2Wheelsonly]

Well, revisiting this two weeks later and my nitrates seemed to have gone up. I am feeding so little and nothing is dead in the tank, also running an ATS with thick mats of algae i'm pulling off.

almost 4 weeks of vinegar, dosing 100ml daily at this point.

My feedings are reef frenzy once daily and just enough to where everything is accounted for within 10 seconds.

So regardless of scientific reason; it appears carbon dosing is not an exact science and will not work in certain tanks? I'd get a sulfur dentirator but I have doubts it will work at this point. I think these nitrates are "stuck" in my tank and it frustrates the ever living crap out of me because they will ONLY go up and eventually I am going to be at 50+. This is a horrible situation where stuff doesn't make sense.

Never knew carbon dosing would end up being a "only if it works in your tank" thing.

 

[Crustaceon]

I’ve always had issues with nitrate reduction via carbon dosing with the typical .03ppm level. It really is the tipping point for many organisms in our tanks to either survive or begin to starve and the sudden explosion in the bacterial population from a carbon source can rapidly bottom out that Po4 level. I’ve been in the same boat with 25ppm nitrates and .03ppm phosphates and have found the best way to use a carbon source for nitrate reduction and not just a maintenance is to add it to the tank in concert with enough Po4 to keep levels above .03ppm. I personally test, dose to get a .1ppm Po4 level and retest before I add a sizable dose of vodka or vinegar. In the case of my 65g system, this was 5ml. I also add a little bit of beneficial bacteria and heavily feed the tank with really oily food, such as pe mysis. I used to use a raw cocktail shrimp on a veggie clip and let my triggers rip it to shreds, lol. There’s something magical when it comes to shrimp blood and causing a bacterial bloom. Within 24 hours, Po4 was right back at .03ppm according to my hanna meter, so I dosed more Po4 and repeated the process. It took a week to get down to 10ppm nitrates, which is where I’m at now. There’s some finesse to it.

 

[Crustaceon]

Also, you’ll know you’re making a decent impact when your skimmer stops smelling like normal skimmate and starts smelling like food that’s past its expiration date. In this case, slightly cloudy water is a positive sign.

 

[Joedubyk]

Changing out filter socks (or pads) twice a week really helps get nitrates down prety quickly. A well stocked fuges well with some water changes.

Luckily, 25 is actually not high, IMO, of nitrates. A lot of the best vendors use 20-30 ppm to get the best colors out of their SPS.

The worst thing you can do is have low phosphate. But if you're only feeding once a day, your corals could be starving (hence the paleness).

 

[Crustaceon]

Changing out filter socks (or pads) twice a week really helps get nitrates down prety quickly. A well stocked fuges well with some water changes.

Luckily, 25 is actually not high, IMO, of nitrates. A lot of the best vendors use 20-30 ppm to get the best colors out of their SPS.

The worst thing you can do is have low phosphate. But if you're only feeding once a day, your corals could be starving (hence the paleness).

100% agree. I’d say anything under 20ppm and above 5ppm nitrates is good. I also started having much greater success with acros once I started running my system at an elevated Po4 level (.08ppm). I think phosphate gets a bad wrap.

 

[Joedubyk]

100% agree. I’d say anything under 20ppm and above 5ppm nitrates is good. I also started having much greater success with acros once I started running my system at an elevated Po4 level (.08ppm). I think phosphate gets a bad wrap.

So does nitrates. WWC is at 20 and one guy who gets the best colors Ive ever seen out of tenuis uses 20-30ppm, and won't go below 10 due to color loss.

The worst crash I ever had was accidentally bottoming out my po4. So, agree with you there. lost thousands....

 

[weamdog]

I've been struggling with the same issue for weeks. Had to pull out all my acro frags which started to get bleached tips and brown algae forming. Mine were up around 75 and are now bouncing around 30-50. Hooked up my denitrator which is undersized for my tank. It's getting rid of nitrates a drop at a time but is also throwing all my other parameters into chaos and my trident is making things worse instead of stabilizing. Working on getting a zeolith reactor, but ran into issues with that transaction. May have to order one from Singapore.

For me, looks like the no3po4x has only impacted po4 so i guess I'm bottomed out until the denitrator can catch up. Po4 went from .19 to .02 in two weeks while nitrate is stuck.

My chaeto isn't helping much either, have the fuge and a reactor, but noticed i was running low on nutrients for it so i had to add some chaetogrow.

 

[Crustaceon]

So does nitrates. WWC is at 20 and one guy who gets the best colors Ive ever seen out of tenuis uses 20-30ppm, and won't go below 10 due to color loss.

The worst crash I ever had was accidentally bottoming out my po4. So, agree with you there. lost thousands....

I figure I’d MUCH rather deal with the first signs of hair algae and slightly balance my nutrient addition/export than seeing everything simultaneously stn or even rtn. Having an acro-dominant system go downhill can be an absolutely devastating loss and even if your tank survives it, you’re talking months to get things to heal up.

 

[weamdog]

Also, you’ll know you’re making a decent impact when your skimmer stops smelling like normal skimmate and starts smelling like food that’s past its expiration date. In this case, slightly cloudy water is a positive sign.

Funny, i have noticed this myself over the past day or so, don't have to hold my nose now. Pretry sure the cause of my issue was chaeto clogging my skimmer and here i thought it was working too good.

 

[Jon_W79]

Well, revisiting this two weeks later and my nitrates seemed to have gone up. I am feeding so little and nothing is dead in the tank, also running an ATS with thick mats of algae i'm pulling off.

almost 4 weeks of vinegar, dosing 100ml daily at this point.

My feedings are reef frenzy once daily and just enough to where everything is accounted for within 10 seconds.

So regardless of scientific reason; it appears carbon dosing is not an exact science and will not work in certain tanks? I'd get a sulfur dentirator but I have doubts it will work at this point. I think these nitrates are "stuck" in my tank and it frustrates the ever living crap out of me because they will ONLY go up and eventually I am going to be at 50+. This is a horrible situation where stuff doesn't make sense.

Never knew carbon dosing would end up being a "only if it works in your tank" thing.

 

[Joedubyk]

I figure I’d MUCH rather deal with the first signs of hair algae and slightly balance my nutrient addition/export than seeing everything simultaneously stn or even rtn. Having an acro-dominant system go downhill can be an absolutely devastating loss and even if your tank survives it, you’re talking months to get things to heal up.

Yep!! Been there!

 

[Jon_W79]

Your denitrifying bacteria and algae probably aren't growing well for the same reasons. I'm guessing there is something missing from the water that they need to grow well. I believe it is very well understood what algae need to grow. If you give your algae what they need to grow well, I think carbon dosing will start to lower your nitrates. From what you said about having pale corals and enough phosphate I think the next thing you should do(If you don't know your iron levels.) is add a significant amount of iron,(You may want to do it slowly.) and then see if it helps your denitrifying bacteria and algae.