Alk rising - not sure why

[IntenseImage]

I've been testing my Alk for awhile now with Salifert kits and recently picked up a Hanna checker to make life a little easier. The Hanna read pretty close to the color guestimate of the Salifert ... And I would dose 2-part accordingly. My demands are pretty low (dosing 1/4oz every few days) when I saw my dkh drop from 9 to 8.9.

Its been a 2-3 days I think since I've last dosed and today the reading is coming in at 9.4! I used the Salifert to check the Hanna and got about the same.

The only other thing I've started to dose is NOPOX to deal with some algae but that would have lowered the alk a little (or so I thought)

What else would be causing my Alk to rise!?

Could it be something in my top off water (failing RODI unit)?

 

[Dom]

I've been testing my Alk for awhile now with Salifert kits and recently picked up a Hanna checker to make life a little easier. The Hanna read pretty close to the color guestimate of the Salifert ... And I would dose 2-part accordingly. My demands are pretty low (dosing 1/4oz every few days) when I saw my dkh drop from 9 to 8.9.

Its been a 2-3 days I think since I've last dosed and today the reading is coming in at 9.4! I used the Salifert to check the Hanna and got about the same.

The only other thing I've started to dose is NOPOX to deal with some algae but that would have lowered the alk a little (or so I thought)

What else would be causing my Alk to rise!?

Could it be something in my top off water (failing RODI unit)?

That doesn't feel like a big increase to me. I'd monitor.

"Every few days" is a bit ambiguous. Chemistry is an exact science. What I'd like to know is this; are the steps you've taken:

Test > 8.9 > Dose > Test >9.4 ?

 

[glb]

I've been testing my Alk for awhile now with Salifert kits and recently picked up a Hanna checker to make life a little easier. The Hanna read pretty close to the color guestimate of the Salifert ... And I would dose 2-part accordingly. My demands are pretty low (dosing 1/4oz every few days) when I saw my dkh drop from 9 to 8.9.

Its been a 2-3 days I think since I've last dosed and today the reading is coming in at 9.4! I used the Salifert to check the Hanna and got about the same.

The only other thing I've started to dose is NOPOX to deal with some algae but that would have lowered the alk a little (or so I thought)

What else would be causing my Alk to rise!?

Could it be something in my top off water (failing RODI unit)?

Did you just do a water change? That can raise alk depending on the salt mix. I use Nopox and haven't noticed it affect alk. Plus there are error percentages for all the tests. I would look up the margin for error for the Hanna. It's also possibly a testing error, maybe not quite as much water in the vial the second time. .4 isn't a huge amount. If this is the first test you've done since dosing, it's also possible you dosed a little more. I'd test it daily for a few days and see what happens. What kind of coral do you have?

 

[IntenseImage]

That doesn't feel like a big increase to me. I'd monitor.

"Every few days" is a bit ambiguous. Chemistry is an exact science. What I'd like to know is this; are the steps you've taken:

Test > 8.9 > Dose > Test >9.4 ?

Ive been trying to test alk daily ... And it will be a few days, normally, for me to see a drop from 9 to 8.9 on the Hanna. When I see it below 9, I dose ... And the next day I'm back to 9 ... Rinse and repeat ...

 

[IntenseImage]

Did you just do a water change? That can raise alk depending on the salt mix. I use Nopox and haven't noticed it affect alk. Plus there are error percentages for all the tests. I would look up the margin for error for the Hanna. It's also possibly a testing error, maybe not quite as much water in the vial the second time. .4 isn't a huge amount. If this is the first test you've done since dosing, it's also possible you dosed a little more. I'd test it daily for a few days and see what happens. What kind of coral do you have?

Nope, last wc was back around the 20th. FWIW when I tested last night it was 9.1 ... Today 9.4 with no dosing between

 

[Dom]

Ive been trying to test alk daily ... And it will be a few days, normally, for me to see a drop from 9 to 8.9 on the Hanna. When I see it below 9, I dose ... And the next day I'm back to 9 ... Rinse and repeat ...

Yeah... i'd just monitor for a few days. If it continues to rise, then we will have to try an determine the cause.

 

[glb]

Nope, last wc was back around the 20th. FWIW when I tested last night it was 9.1 ... Today 9.4 with no dosing between

I'd keep testing it daily to show a pattern.

 

[Randy Holmes-Farley Verified Community Expert]

I've been testing my Alk for awhile now with Salifert kits and recently picked up a Hanna checker to make life a little easier. The Hanna read pretty close to the color guestimate of the Salifert ... And I would dose 2-part accordingly. My demands are pretty low (dosing 1/4oz every few days) when I saw my dkh drop from 9 to 8.9.

Its been a 2-3 days I think since I've last dosed and today the reading is coming in at 9.4! I used the Salifert to check the Hanna and got about the same.

The only other thing I've started to dose is NOPOX to deal with some algae but that would have lowered the alk a little (or so I thought)

What else would be causing my Alk to rise!?

Could it be something in my top off water (failing RODI unit)?

No, organic carbon dosing reducing nitrate (meaning it is declining) raises alk, it doesn't deplete it.

The alkalinity gain is 0.8 meq/L (2.3 dKH) for every 50 ppm of nitrate consumed.

 

[IntenseImage]

No, organic carbon dosing reducing nitrate (meaning it is declining) raises alk, it doesn't deplete it.

The alkalinity gain is 0.8 meq/L (2.3 dKH) for every 50 ppm of nitrate consumed.

Ah ... My nitrates have been dropping a little since I've been using nopox (going on 2 weeks now) so that could be it!