Alk solution precipitates when adding it to the tank

[Acalin]

Hello all,

For about 2-3 days I noticed my Alk started to drop.
I started noticing this around the same time when I started to add a bit of Mg solution (Foundation Magnesium from Red Sea) and the reason I started adding Mg was because its level was dropping too and got to around 1276 ppm.
Up until this evening I kept increasing slowly the dosage for Alk solution (I am suing KH Plus from AquaForest) but my Alk level still didn't seem to go up at all.
This evening, I took a look in the sump as I was trying to pump a bit of Alk solution and noticed that as soon as the solution hits the water it precipitates. Thinking the flow might be too low, because I am dosing in the return pump compartment in the sump, I decided to put a few drops directly in the DT, right at the return pump nozzle and the same thing happened.

So now I am not sure what is wrong.
One of the causes, likely is the low nutrient system. I was running the skimmer continuously for the past few days, so my phosphates and nitrates are 0, although I don't know how true of a measurement it is, because my sump still grows hair algae.

For the other parameters:
Salt: 35 ppt (used to be around 35.5, but today I've added a bit more RODI water)
Temp: 78F on average (fluctuates from 77.5 to 78.5)
PH: 8.2 at night and 8.33 during daytime.
Alk: currently sitting at 8.79 (my target is around 9 - 9.1 dKH)
CA: 399 PPM
MG 1316 PPM

Any suggestions on what I should do to stop the Alk solution precipitating?

I am not sure if it's related, I would assume it would be related to the drop in Alk, but one of my Acropora Millepora started dying. Looks like RTN because in about 1.5 days, more than half of it lost the tissue.
I do have the original colony as well in the tank (this was just a frag that started growing into a colony as well) but the original one doesn't seem to be affected.

LATER EDIT: After dosing a bit more than usual, trying to figure out whether dripping in the pumps flow would eliminate the issue, I re-ran a test. (at 7PM my Alk reading was 8.79 dKH and 2.5 hours later at 9:22 PM, my alk dropped to 8.73 dkH). Looks like all that I dosed while playing around did not get dissolved.
My other concern is: what if it starts dissolving and then my alk is going to spike. So I have no clue what to do now.

Thank you in advance for all your advice!

 

[KrisReef]

Lower your target.
Dilute your add mixes.

 

[ptrick21186]

What do you mean by "precipates out"?

 

[mike550]

I’m guessing you’re using soda ash solution to raise your Alk. The cloudiness is fine and is from a a sudden spike in concentration. Dose it into high flow areas like a Powerhead or pump at a low rate.

 

[stlamarc]

I was told that if Alkalinity is hardly moving up after dosing that Mag is probably too low. But I'll let the experts chime in on this...

 

[Acalin]

Lower your target.
Dilute your add mixes.

I am dosing separately the Alk, Ca and MG.
I am not too familiar with the dilution procedure. Would I just mix RODI with water?
I am using Neptune DOS (and Trident for measurements) and my Alk cylinder is almost full. I can take out some of the solution to add water, but in that case wouldn't it mess up my dosage?

What do you mean by "precipates out"?

it forms white particles.

 

[ptrick21186]

Large particles or a cloud that quickly dissipates into the water column? Or I should say long lasting particles....

 

[Acalin]

I’m guessing you’re using soda ash solution to raise your Alk. The cloudiness is fine and is from a a sudden spike in concentration. Dose it into high flow areas like a Powerhead or pump at a low rate.

I am using KH Plus from Aquaforest Lab and the container says it contains sodium hydroxide.
I did try to drip right into the output nozzle of the return pump (which I think it's high flow) but as soon as the solution touched the water it precipitated, no matter how slow I was dripping.

 

[Acalin]

Large particles or a cloud that quickly dissipates into the water column? Or I should say long lasting particles....

It's certainly not a cloud. It breaks into small particles. I was trying to look closer as they get through the power heads to see if they dissolve and it seems like they do dissolve, but then again, I have a bunch of small white particles flowing in my tank which I am pretty sure are because of the Alk solution.
Furthermore, if they would dissolve, I would expect my Alk test to read higher.
I did a test, added a bit of Alk solution, waited to get it circulated through the tank a bit to dissolve (if it does dissolve, because I can't confirm this 100%) and then re-ran the test. Test read the same as before adding the solution.

 

[KrisReef]

I’m not going to provide you with more advice on your chemistry set. NaOh (Sodium Hydroxide) is not working in my tank, I use a calcium reactor, sorry.

 

[Acalin]

I’m not going to provide you with more advice on your chemistry set. NaOh (Sodium Hydroxide) is not working in my tank, I use a calcium reactor, sorry.

Sir, I have limited to no chemistry knowledge, so any piece of advice is welcome!

 

[Acalin]

It's certainly not a cloud. It breaks into small particles. I was trying to look closer as they get through the power heads to see if they dissolve and it seems like they do dissolve, but then again, I have a bunch of small white particles flowing in my tank which I am pretty sure are because of the Alk solution.
Furthermore, if they would dissolve, I would expect my Alk test to read higher.
I did a test, added a bit of Alk solution, waited to get it circulated through the tank a bit to dissolve (if it does dissolve, because I can't confirm this 100%) and then re-ran the test. Test read the same as before adding the solution.

Here is a link to a video I've done with the phone. Pretty hard to see with all the blue light but I was able to catch a better view of those particles I am talking about towards the middle of the video.

 

[Randy Holmes-Farley]

It is normal to see magnesium hydroxide precipitate where any high pH additive first mixes with the water. It should redissolve as it mixes in, but if it does not, it may proceed to precipitate calcium carbonate that will not redissolve.

If you are concerned that the particles are not redissolving, you can switch to a lower pH alk supplement, such as baking soda, or you can dilute the additive you are using with RO/DI and add it more slowly and/or more spread out in the day.