alk precipitating

Susan Edwards · Dec 31, 2021

I have been manually dosing. I dose 30-60 min apart (ca/alk/mg twice a day. Last night I notice when I added the alk it precipitated--turned clumpy/flakey in the return chamber. This morning, 6 hours later, I dosed alk first, and it did the same thing. I added it slowly as well.

Why all of a sudden is the alk doing this? I plan to vacuum the chamber after work (gravel vac into a filter sock) and scrape the bottom what I can with 2 pumps in there, and cleans the sides. I'll be setting up my doser in the next few days and will split the amt (40 ml day) into the 24 hrs along with the other 2 additives but would like to know why the issues all of a sudden

shwareefer · Dec 31, 2021

I think you have to stop dosing. Do testing of your big 3 and report back. This probably would do better in the chemistry forum.

redfishbluefish · Dec 31, 2021

Moved to Reef Chemistry Forum.

Susan Edwards · Dec 31, 2021

alk 8.7, ca 380, mg 1440

If I stop, those numbers will drop. Maybe stop for a day? I test every 3 for 4 days. Tank is an upgrade almost 3 months old. 240 total water vol. RS 3xl 900

Randy Holmes-Farley · Dec 31, 2021

What are you dosing? How much at once in dKH units (not mL).

It is normal to see a temporary precipitate when dosing a high pH additive. It is magnesium hydroxide that redissolves as it mixes in.

If it does not mix in fast enough, calcium carbonate can begin to precipitate locally, and that won't redissolve.

If you are concerned about calcium carbonate precipitation, use a lower pH alk additive, diluted more, added more slowly to a higher flow area.

Randy Holmes-Farley · Dec 31, 2021

This is normal:

What is that Precipitate in My Reef Aquarium? by Randy Holmes-Farley - Reefkeeping.com

Figure 3. The transient cloud of magnesium hydroxide that forms when high pH additives are added. In this case, the alkalinity portion of B-ionic was added to a fairly still portion of one of my reef aquaria.

Susan Edwards · Dec 31, 2021

Randy Holmes-Farley said:
What are you dosing? How much at once in dKH units (not mL).

It is normal to see a temporary precipitate when dosing a high pH additive. It is magnesium hydroxide that redissolves as it mixes in.

If it does not mix in fast enough, calcium carbonate can begin to precipitate locally, and that won't redissolve.

If you are concerned about calcium carbonate precipitation, use a lower pH alk additive, diluted more, added more slowly to a higher flow area.

I'm not sure how much in dkh units. I use the BRS soda ash, dosing 20 ml 2x's a day all at once each time. Usually I just see the white cloud, not the clumps. I'll try dosing slower. Working on getting my doser set up. I'll also add some ro water to the shot glass.

I also use the BRS Cal and Mag. I had some ESV so not sure if I'm still on the last of the ESV mg.

It just caught me by surprise last night

Susan Edwards · Dec 31, 2021

Yes, that

Randy Holmes-Farley said:
This is normal:

What is that Precipitate in My Reef Aquarium? by Randy Holmes-Farley - Reefkeeping.com

Figure 3. The transient cloud of magnesium hydroxide that forms when high pH additives are added. In this case, the alkalinity portion of B-ionic was added to a fairly still portion of one of my reef aquaria.

Yes, that is what I normally get in the sump but even 6 hrs later from last night to this am, it was clumpy not smokey looking. I'll try again later tonight

Morpheosz · Jan 17, 2022

Similar issue here, I just started dosing BRS soda ash in my newly setup tank. I'm using a DOS pump and when it drips into the sump, it appears to immediately become snowflakes vs a cloud. Will this dissolve on its own or is this a problem? My alk is 9.0dkh, it dropped from 9.2 -> 9.0 in 2 days so I started a small dosing regimen to try to stabilize it at 9.0. My ph is 8.1, Ca is 430, salt 35ppt.

Ippyroy · Jan 17, 2022

I had the same issue. It was caused by dosing when I didn't need to. If your Dkh remains steady via water changes, you don't need to dose. I had it building up in the sand and I made a lot of very solid hard rocks.

Randy Holmes-Farley · Jan 17, 2022

Morpheosz said:
Similar issue here, I just started dosing BRS soda ash in my newly setup tank. I'm using a DOS pump and when it drips into the sump, it appears to immediately become snowflakes vs a cloud. Will this dissolve on its own or is this a problem? My alk is 9.0dkh, it dropped from 9.2 -> 9.0 in 2 days so I started a small dosing regimen to try to stabilize it at 9.0. My ph is 8.1, Ca is 430, salt 35ppt.

As I noted above, cloudiness is normal and redissolution is normal.

if it is not redissolving, that is a concern.

You can dose baking soda instead if you want less concern about precipitation. Also, dilute it more with RO/DI before dosing and dose to a higher flow area.