Alkalinity and calcium rising without dosing

[riley.jones01]

As stated in the title, my alkalinity and calcium have been rising steadily for the last 2-3 months. Currently, my dKh is sitting at somewhere around 10.5-10.8. Trident says 10.57, Hanna checker says 10.8, and salifert says 10.6.

Calcium is sitting at 527, salifert said 520ish so the trident seems to be fairly accurate.

Mg is sitting at 1303 as of last night (per trident), I added a 600ml dose of ESV magnesium, calculated with the reefing calculator, to bring it back to 1350 this evening. Magnesium has been slowly consumed while the other two have slowly risen.

Coral load isnt crazy, I've got a good amount of zoas and mushrooms, a small goniopora garden, and a half dozen 1" acro frags which dont seem to be growing but do have good polyp extension and color. There was a ton of euphylia in the tank but an alk swing, again with no dosing, killed all of it off a few months back.

I have not done any water changes (yet) nor have i dosed any calcium or alk additives. Currently, the only things being added into the tank are:

ATO water - ICP confirms, nothing but small amount of silicate in the ATO
Reef moonshiners Ru, I, Mn, Cr, Co, Fe, and liquid mud which was added last week, all of which are tiny tiny daily doses.
NOPOX - NO3 and PO4 were getting out of hand from my fish load, NO3 was at 56 mg/l and PO4 at 0.93mg/l (terrible, i know)

ICP says my salinity is at 32.08PSU, which to my understanding is about 1.024?

I started the tank in ~march of this year using marco rock, and CaribSea Ocean direct live sand. Tank volume is ~490L with the sump. Could my sand or marco rock be "dissolving" and leaching to raise my dKh and calcium?

Im prepping a 25g water change with red sea blue bucket salt right now, dKh usually mixes around 7.8. If I did my math correctly, that should lower my alk from 10.57 to about 10.1. Id like it to be down closer to 8.


Why is my alk and calcium rising while i am adding nothing? Thanks in advance!

 

[blaxsun]

Very weird. I'd maybe start doing more regular water changes (at least once a month) to see what if any effect that has.

 

[Randy Holmes-Farley]

The usual cause is very low demand, coupled of nitrate declining (boosts alk) or calcium carbonate sand slowly dissolving down in it where pH can be lower.

Test error and changing salinity is also a common "cause".

 

[riley.jones01]

@Randy Holmes-Farley thank you for your reply. What should I do to correct these potential issues?

 

[Randy Holmes-Farley]

@Randy Holmes-Farley thank you for your reply. What should I do to correct these potential issues?

Are you tracking nitrate?

 

[riley.jones01]

@Randy Holmes-Farley Not as often as I probably should be. I’ve been testing it every other week with salifert and monthly with ICP. It has been very high, ~40 consistently.

 

[Randy Holmes-Farley]

If nitrate is steady at any level, then it is not the cause of risng alk.

If you are confident in the rise in alk (rather than test issues), then the choices are:

1. Water changes with a lower alk mix (you can make it as low as you want)
2. Slowly adding an acid (essentially, depletes alk when added) such as sodium bisulfate or muriatic acid
3. Increase organisms in the tank that consume alkalinity and calcium
4. Try removing the sand or replacing it with something else.

1-3 are guaranteed to work. 4 may or may not solve the issue.

 

[riley.jones01]

@Randy Holmes-Farley Thank you for the reply. If I was to dose muriatic acid, what sort of dosing would i need to do and what would the potential downside to dosing it be?

Alk is back up to 10.8 after doing a 40 gallon water change last Wednesday night. Nothing dosed since.

 

[Randy Holmes-Farley]

@Randy Holmes-Farley Thank you for the reply. If I was to dose muriatic acid, what sort of dosing would i need to do and what would the potential downside to dosing it be?

Alk is back up to 10.8 after doing a 40 gallon water change last Wednesday night. Nothing dosed since.

Two options are direct dosing (needs to be very slow and careful to prevent a big pH drop), or lowering the alk in your water change water (which you can aerate to bring the pH back up before using).

Here's the bisulfate directions:

Sodium Bisulfate to Reduce Alkalinity in New Salt Water or in Display Tanks

I just want to record these calculations in their own thread to refer back to in other threads. When alkalinity is too high in new salt water or in a display tank, acid can be used to lower the alkalinity. You can easily use muriatic acid (hydrochloric acid), or sodium bifulfate (e.g...

www.reef2reef.com

and here are muriatic acid calculations which assumes you are doing it in new salt water, not a reef tnak. YOu must go very slow in a reef tank.



Be very careful with straight muriatic acid. It can easily burn you, especially your eyes.

The "acidity" (that being essentially negative alkalinity) of normal (not low fume type) muriatic acid straight from the bottle is about 11,000 meq/L.

So adding 1/11,000 of the water volume as this acid will drop alkalinity by 1 meq/l (2.8 dKH).

You want a drop of 13-7 = 6 dKH, or 2.1 times that amount, so you'd add 1/5,100th of the water volume.

13 gallons ~ 49 L

1/5100 of 49 L = 9.6 mL

So I'd add 5 ml and stir well for a few minutes and see what alkalinity you get. Then dose again assuming it seems on the right track.

You'll need to aerate well after adding the acid to blow off the excess CO2 and bring up the pH.

 

[3dogsandreefing]

As stated in the title, my alkalinity and calcium have been rising steadily for the last 2-3 months. Currently, my dKh is sitting at somewhere around 10.5-10.8. Trident says 10.57, Hanna checker says 10.8, and salifert says 10.6.

Calcium is sitting at 527, salifert said 520ish so the trident seems to be fairly accurate.

Mg is sitting at 1303 as of last night (per trident), I added a 600ml dose of ESV magnesium, calculated with the reefing calculator, to bring it back to 1350 this evening. Magnesium has been slowly consumed while the other two have slowly risen.

Coral load isnt crazy, I've got a good amount of zoas and mushrooms, a small goniopora garden, and a half dozen 1" acro frags which dont seem to be growing but do have good polyp extension and color. There was a ton of euphylia in the tank but an alk swing, again with no dosing, killed all of it off a few months back.

I have not done any water changes (yet) nor have i dosed any calcium or alk additives. Currently, the only things being added into the tank are:

ATO water - ICP confirms, nothing but small amount of silicate in the ATO
Reef moonshiners Ru, I, Mn, Cr, Co, Fe, and liquid mud which was added last week, all of which are tiny tiny daily doses.
NOPOX - NO3 and PO4 were getting out of hand from my fish load, NO3 was at 56 mg/l and PO4 at 0.93mg/l (terrible, i know)

ICP says my salinity is at 32.08PSU, which to my understanding is about 1.024?

I started the tank in ~march of this year using marco rock, and CaribSea Ocean direct live sand. Tank volume is ~490L with the sump. Could my sand or marco rock be "dissolving" and leaching to raise my dKh and calcium?

Im prepping a 25g water change with red sea blue bucket salt right now, dKh usually mixes around 7.8. If I did my math correctly, that should lower my alk from 10.57 to about 10.1. Id like it to be down closer to 8.


Why is my alk and calcium rising while i am adding nothing? Thanks in advance!

Were you able to figure this out? I am doing Reef Moonshiners and no water changes and having the same issue. High dKh without Alk dosing. Tested using GHL and Hanna. dKh will move between 9.6 and 10.4. Although it has not been higher than this.

Previously I would dose 30ml a day and dKh would be around 8.5. Now no dosing and staying at 10.4. Only dose Moonshiners dailies.

 

[Randy Holmes-Farley]

If nitrate is not declining and you use RO/DI for top off, then the most likely explanation is sand and rock slowly dissolving.

Some of the additives may also add alk, depending on what you are adding.