Very low ALK

[Emery]

Hey Guys, hope all is well and everyone is healthy during the pandemic. I have a question on alkalinity in a biocube I set up on my desk at work. 29g with maybe 25g of actual water. It’s been run in for about 3 months, and there’s 4 fish and no coral in the tank yet.

Every morning I get to work I test my Alk at 6am and my Alk is in the mid 5s (5.5, 5.3, 5.6). I’ve been trying to get it up to the 8.0 range for the last two weeks. First I dosed 2 part to get my alk to 8.0 and calcium to 450. Then fired up a kalk reactor thinking that would do the job of holding the levels in that range. It’s not. I test the next morning and mid 5s again. The last week I’ve been dosing 20ml of bionic 2 part daily and I still can’t get a boost in Alk. I’ve checked with both Hanna and salifert testers which are within .3 dkh of each other so the number seems to be real to me.

I do a 5 gallon water change every 2 weeks with Red Sea blue. The rest of my numbers are as follows:
Alk- 5.5 (Hanna and salifert)
Cal- 445 (salifert)
Mag- 1440 (salifert)
Nitrate- 5 (salifert)
Phosphate- 0 (Hanna and salifert)

At this point I’m at a loss and don’t know what to do. Having no coral in the tank I don’t know what’s sucking it all up, and if it’s precipitating out, I don’t know how I get it to stop precipitating. Any ideas or suggestions to help me out would be much appreciated.

Thank you,

 

[Emery]

Salinity is 1.025

 

[Fred2482]

Is there any type of algae in the tank?

 

[Emery]

No algae at all

 

[Cunning_plan]

Have you calibrated your refractometer?

 

[LegendaryCG]

Are you dosing acids? Sounds like a crazy drop overnight with no coral.

 

[Miller535]

I would say one of two things is happening, especially since you have no coral and probably no coraline to be uptaking the alk.

1. Your salinity is actually lower then you think, perhaps a refractometer not calibrated as already stated.

2. You either have a faulty alk test kit, or user error.


A side not to adding soda ash (assuming this since you said 2 part), unless added very slowly into high flow area a lot of it will precipitate out, and either clump on heaters or cause the sand itself to turn into hard clumps. I had this happen myself with both Kalkwasser and 2 part.

 

[Emery]

Have you calibrated your refractometer?

Yea I have the 35ppt calibration solution. I’ve calibrated and check the tank and it 1.025

Are you dosing acids? Sounds like a crazy drop overnight with no coral.

The only thing I’ve put in the tank was MB7 early on, the kalkwasser, and B-ionic 2 part.

 

[Randy Holmes-Farley]

When you dosed to 8 dKH, how fast did it fall back?

 

[Emery]

I would say one of two things is happening, especially since you have no coral and probably no coraline to be uptaking the alk.

1. Your salinity is actually lower then you think, perhaps a refractometer not calibrated as already stated.

2. You either have a faulty alk test kit, or user error.


A side not to adding soda ash (assuming this since you said 2 part), unless added very slowly into high flow area a lot of it will precipitate out, and either clump on heaters or cause the sand itself to turn into hard clumps. I had this happen myself with both Kalkwasser and 2 part.

I double checked the salinity after calibrating and tank water is still 1.025. I thought the kit might have been bad so I bought a salifert from my LFS and it was within .3 of the Hanna tests I’ve been running.
As far as the sand clumping, I vacuum the sand every water change and it’s not hard. Maybe I should try to put a doser on the tank and dosenin smaller increments tho.

 

[Emery]

When you dosed to 8 dKH, how fast did it fall back?

The next morning at 6am it was back to 5.4

 

[Super Fly]

is there coralline algae growing anywhere?

 

[Emery]

is there coralline algae growing anywhere?

No

 

[Randy Holmes-Farley]

I think that, if the measurements are accurate, it has to be due to abiotic precipitation of calcium carbonate.

I'd advise stopping all alk dosing for at least a week. When you restart, do not go over 7 dKH, and do so only with baking soda.

You want the ongoing precipitation to stop and for the crystal surfaces to become "clogged" with magnesium, phosphate, and organics, and for pH and alk to be low.

 

[Emery]

I think that, if the measurements are accurate, it has to be due to abiotic precipitation of calcium carbonate.

I'd advise stopping all alk dosing for at least a week. When you restart, do not go over 7 dKH, and do so only with baking soda.

You want the ongoing precipitation to stop and for the crystal surfaces to become "clogged" with magnesium, phosphate, and organics, and for pH and alk to be low.

Thanks Randy, all that is way above my pay grade. But I will let the tank sit dor a week or two, the. Start with the baking soda.

 

[Emery]

I think that, if the measurements are accurate, it has to be due to abiotic precipitation of calcium carbonate.

I'd advise stopping all alk dosing for at least a week. When you restart, do not go over 7 dKH, and do so only with baking soda.

You want the ongoing precipitation to stop and for the crystal surfaces to become "clogged" with magnesium, phosphate, and organics, and for pH and alk to be low.

Should I also take the kalk reactor offline for a week or so?

 

[Randy Holmes-Farley]

Should I also take the kalk reactor offline for a week or so?

Yes. It would be the last thing to restart.

 

[Miller535]

I think that, if the measurements are accurate, it has to be due to abiotic precipitation of calcium carbonate.

I'd advise stopping all alk dosing for at least a week. When you restart, do not go over 7 dKH, and do so only with baking soda.

You want the ongoing precipitation to stop and for the crystal surfaces to become "clogged" with magnesium, phosphate, and organics, and for pH and alk to be low.

What do you mean by crystal surfaces?

 

[Randy Holmes-Farley]

What do you mean by crystal surfaces?

When calcium carbonate precipitates to form a solid, the surface of those solid chunks are attracting more calcium and more carbonate, thus it keeps on collecting more and more calcium carbonate until the cycle is broken somehow.

This describes the process more:

http://reefkeeping.com/issues/2006-06/rhf/index.php

 

[Miller535]

When calcium carbonate precipitates to form a solid, the surface of those solid chunks are attracting more calcium and more carbonate, thus it keeps on collecting more and more calcium carbonate until the cycle is broken somehow.

This describes the process more:

http://reefkeeping.com/issues/2006-06/rhf/index.php

Ah, I see. Thanks