Alkalinity drop

[56longroof]

I started running a Donovan Nitrate Destroyer a week ago. Im not sure if its related but Im having trouble keeping alk at my desired level. I try to run it at 8-9 and now its staying at 6-6.7. I increased the potency in the ATO from half to 3/4 saturation kalk with no results. I also tried 2 different Salifert test kits with almost identical results. Nothing else has changed except a new batch of AFR was mixed up. I always mix it heavy so there is some of the powder in the bottom of the jug that wont mix. Any ideas?

 

[Uncle99]

It’s like nopox, a carbon dose which can lower alk, so not overly surprised it lowers Alk.

You’ll need to counter the Donavan’s with small Alk increases, not more than .5 dkh per day.

Might take a bit.

 

[backbayreef]

Something smells fishy - it’s unlikely that doing some sorts of sulfur denitrifications or carbon dosings would drop Alk that low. Are you saying that it dropped from 8-9ish to 6-7ish? I run a huge Aquamaxx TS-3 sulfur denitrator and Alk consumption was marginal — 0.2dKh/day on a 450gal tank. Also, with sulfur denitrification, it would take 4-6 weeks for bacteria to colonize.

What are you using to test Alk? I would start looking at that first.

 

[56longroof]

I have been carbon dosing the tank for over a year. If anything I've cut back on that some and dose it in the DND now. I still add a smaller amount in the sump though.

It’s like nopox, a carbon dose which can lower alk, so not overly surprised it lowers Alk.

You’ll need to counter the Donavan’s with small Alk increases, not more than .5 dkh per day.

Might take a bit.

 

[56longroof]

Something smells fishy - it’s unlikely that doing some sorts of sulfur denitrifications or carbon dosings would drop Alk that low. Are you saying that it dropped from 8-9ish to 6-7ish? I run a huge Aquamaxx TS-3 sulfur denitrator and Alk consumption was marginal — 0.2dKh/day on a 450gal tank. Also, with sulfur denitrification, it would take 4-6 weeks for bacteria to colonize.

What are you using to test Alk? I would start looking at that first.

I rarely test anymore. I tested alk about 3 weeks ago and it was fine. I've been using Salifert from day 1 with no issues. I even verified with a brand new kit.

 

[Randy Holmes-Farley Verified Community Expert]

Reducing nitrate will boost alk, unless it’s done in a sulfur denitrator.

 

[56longroof]

Reducing nitrate will boost alk, unless it’s done in a sulfur denitrator.

Thats what has me wondering what's going on. Im starting to think the new container of AFR might be the issue.

 

[JGT]

Wouldn’t carbon dosing, even in a DND, reduce alkalinity if you were using vinegar?

 

[56longroof]

Wouldn’t carbon dosing, even in a DND, reduce alkalinity if you were using vinegar?

I saturate it with kalk

 

[Randy Holmes-Farley Verified Community Expert]

Wouldn’t carbon dosing, even in a DND, reduce alkalinity if you were using vinegar?

No. Vinegar has no lasting impact on alk once it is metabolized.

If nitrate reduces in the process, alk rises by 2.3 dKH per 50 ppm of nitrate reduced.

 

[JGT]

No. Vinegar has no lasting impact on alk once it is metabolized.

If nitrate reduces in the process, alk rises by 2.3 dKH per 50 ppm of nitrate reduced.

Interesting. So we add kalk to offset PH drop?

 

[56longroof]

Interesting. So we add kalk to offset PH drop?

Yep

 

[Randy Holmes-Farley Verified Community Expert]

Interesting. So we add kalk to offset PH drop?

It's especially useful if you do once a day manual dosing. It prevents any ph drop on initial addition. I used that before I got a dosing pump for the vinegar.

Once I got a pump I went to dosing straight vinegar speard over the daylight hours.

In my current tank I do not use organic carbon dosing and actually dose ammonia.

 

[Idech]

In my current tank I do not use organic carbon dosing and actually dose ammonia.

What are the benefits of dosing ammonia ? Doesn’t it increase your nitrates or maybe that’s what you want ?

 

[Randy Holmes-Farley Verified Community Expert]

What are the benefits of dosing ammonia ? Doesn’t it increase your nitrates or maybe that’s what you want ?

Yes, I want to boost availability of N:

https://www.reef2reef.com/threads/diy-ammonia-dosing-for-low-nitrate-systems.987087/

 

[backbayreef]

I rarely test anymore. I tested alk about 3 weeks ago and it was fine. I've been using Salifert from day 1 with no issues. I even verified with a brand new kit.

I use Hanna (and Trident) and have not used Salifert in years now. I suspect it’s a testing / test kit error, unless you are indeed consuming 3dKh in 3 weeks, which could happen on a heavy SPS tank, 1dKh/week might sound about right. Your AFR is lagging so not keeping up?

I dose BRS 2-parts and to get alk to stabilize, I test everyday for 3-5days to dial in consumption rate. Attached is my Alk - around 8dKH every 24hr tests.

 

[56longroof]

I use Hanna (and Trident) and have not used Salifert in years now. I suspect it’s a testing / test kit error, unless you are indeed consuming 3dKh in 3 weeks, which could happen on a heavy SPS tank, 1dKh/week might sound about right. Your AFR is lagging so not keeping up?

I dose BRS 2-parts and to get alk to stabilize, I test everyday for 3-5days to dial in consumption rate. Attached is my Alk - around 8dKH every 24hr tests.

The tank is SPS heavy. It can't be a testing error. I've been testing the same way for 2 years and opened a new test kit to verify it was reading correctly. The new kit read the same as the one Im currently using. It has to be either a bad batch of AFR or something related to the nitrate destroyer. Thats the only thing that has changed.

 

[backbayreef]

The tank is SPS heavy. It can't be a testing error. I've been testing the same way for 2 years and opened a new test kit to verify it was reading correctly. The new kit read the same as the one Im currently using. It has to be either a bad batch of AFR or something related to the nitrate destroyer. Thats the only thing that has changed.

Then if would likely point to the last batch of AFR and a combo of higher consumption rate to drop your alk. It’s unlikely the DND since it will take a long time for bacteria to colonize and make material dent to nitrate, hence alk reduction.

 

[56longroof]

Is there a way to test the alk in AFR to verify?

 

[Randy Holmes-Farley Verified Community Expert]

Then if would likely point to the last batch of AFR and a combo of higher consumption rate to drop your alk. It’s unlikely the DND since it will take a long time for bacteria to colonize and make material dent to nitrate, hence alk reduction.

There is no alk reduction from nitrate reduction. It raises alk.