What is eating up my alkalinity?

[blub_blub]

So far I have a few snails, a pistol shrimp, a yellow watchman goby, and a royal gramma. I thought alkalinity mainly got consumed by corals but I am still seeing a .5-1dkh drop in alkalinity per day. Is this normal? What is causing it to drop so much? Using the Salifert test so readings are within ~0.3 accuracy.

Going on a trip next month and trying to get it sorted with simple care instructions before leaving. Perhaps I need to get a drip system but I’d worry about overdosing it without knowing why it’s dropping so much. Also, I see people add Kalkwasser to their ATO reservoir. Waiting on a better calcium test kit to arrive but if I don’t need to bring up calcium, would adding just the Red Sea alkalinity supplement to the ATO reservoir be an option?

Thanks in advance!

 

[get-salty]

Are you using an ATO to top off your tank?

 

[blub_blub]

Are you using an ATO to top off your tank?

Yes

 

[Mr. Mojo Rising]

Do you have coraline growing in the tank?

 

[Randy Holmes-Farley Verified Community Expert]

Can you post a tank picture?

 

[blub_blub]

Do you have coraline growing in the tank?

There are two tiny purple patches on a snail shell. Then there’s a ton of hard green algae but not sure what type. That developed slowly and evenly, not in patches. Will attach a photo

 

[blub_blub]

Sorry for the glare!

 

[Randy Holmes-Farley Verified Community Expert]

Ok, I expect the alk (and calcium) is precipitating onto the existing calcium carbonate surfaces.

How high are you trying to keep it?

 

[blub_blub]

Just got the calcium test in, 360.

Alkalinity was down to 6 when I checked it two weeks ago. Been trying to bring it up to like 8-9

 

[blub_blub]

Ok, I expect the alk (and calcium) is precipitating onto the existing calcium carbonate surfaces.

How high are you trying to keep it?

Why is this happening? Is it normal? Any way to minimize this effect?

Thanks so much for the help troubleshooting!!

 

[Fish Fan]

Just got the calcium test in, 360.

Alkalinity was down to 6 when I checked it two weeks ago. Been trying to bring it up to like 8-9

When both Alk and Calc are low, I would double check your salinity. What are you using to test salinity, and how have you calibrated it?

 

[blub_blub]

Checked salinity a few days ago, 1.026 but will recheck. Using a refractometer. Calibrated with just ro di water but open to getting a solution to calibrate

 

[maxs]

Checked salinity a few days ago, 1.026 but will recheck. Using a refractometer. Calibrated with just ro di water but open to getting a solution to calibrate

Randy Holmes Farley (the guy up there who commented) made an awesome article on calibration solution. A mixture of iodized table salt and RO water for an exact 35ppt solution. You must calibrate your refractometer with 35ppt solution.

 

[Fish Fan]

Checked salinity a few days ago, 1.026 but will recheck. Using a refractometer. Calibrated with just ro di water but open to getting a solution to calibrate

Randy Holmes Farley (the guy up there who commented) made an awesome article on calibration solution. A mixture of iodized table salt and RO water for an exact 35ppt solution. You must calibrate your refractometer with 35ppt solution.

Here's Randy's article with instructions on making your own 35 ppt standard solution. I think this is a good idea, so many "problems" stem an incorrectly calibrated salinity tester:
https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/

 

[Randy Holmes-Farley Verified Community Expert]

Why is this happening? Is it normal? Any way to minimize this effect?

Thanks so much for the help troubleshooting!!

It always happens to some extent, but happens far faster in new tanks with dead rock or sand, with higher pH, and with higher alkalinity.

For now, I’d stop dosing alk and let a variety of other things (phosphate, magnesium, organics, bacteria) coat the surfaces to reduce the effect.

 

[Piotrek]

Checked salinity a few days ago, 1.026 but will recheck. Using a refractometer. Calibrated with just ro di water but open to getting a solution to calibrate

I used to check with refractometer and found the results were very inconsistent. I noticed that repeating the measuring 3 times in a raw (either drying the refractometer in between or not) produced results from 1,021 to 1,026. Different every time I supplied new water dose with a pipette. Perhaps I was doing the measurement wrong, and it was my fault. It took me a few months to notice that. Before I always thought I had to adjust, since the system was very small (10gallons or less).
Instead of trying to become a better person, eventually I purchased a Hanna salinity meter, which I recommend.

 

[blub_blub]

Why is this happening? Is it normal? Any way to minimize this effect?

Thanks so much for the help troubleshooting!!

It always happens to some extent, but happens far faster in new tanks with dead rock or sand, with higher pH, and with higher alkalinity.

For now, I’d stop dosing alk and let a variety of other things (phosphate, magnesium, organics, bacteria) coat the surfaces to reduce the effect.

Oh interesting! That is super counterintuitive to me! Should I make sure it stays above a lower bound or just let it sort itself out entirely? Will the snails and shrimp be alright with a lower alkalinity for a while?

 

[Sam7]

Oh interesting! That is super counterintuitive to me! Should I make sure it stays above a lower bound or just let it sort itself out entirely? Will the snails and shrimp be alright with a lower alkalinity for a while?

It doesnt seem you have anything that needs to be dosed for. Just water changes should do ya

 

[Randy Holmes-Farley Verified Community Expert]

This is my generic paste and copy response for excessive precipitaiton. In this case, I'd wait longer sicne there's little real demand (the snails only).

Bare rock and sand can act as seed crystals for precipitation of calcium carbonate. That is likely adding to the demand. You will have to let it get coated in phosphate, organics, bacteria, etc, and meanwhile slow down the precipitation.

Once it starts it becomes self sustaining since seawater is supersaturated in calcium carbonate.

This is my generic recommendation for excessive precipitation issues (such as hardening sand):

1. Stop all efforts to boost pH.
2. Stop dosing alk for a bit and let it decline.
3. Reduce pH by switching to a low pH alk mix like sodium bicarbonate, or a calcium organic such as Tropic Marin All for Reef.
4. Ensure magnesium is normal to high.
5. Keep organics and phosphate on the high side.

After a few days of not dosing alk, restart slowly, adding additives to a very high flow area so it mixes in fast.

 

[JonasRoman]

So far I have a few snails, a pistol shrimp, a yellow watchman goby, and a royal gramma. I thought alkalinity mainly got consumed by corals but I am still seeing a .5-1dkh drop in alkalinity per day. Is this normal? What is causing it to drop so much? Using the Salifert test so readings are within ~0.3 accuracy.

Going on a trip next month and trying to get it sorted with simple care instructions before leaving. Perhaps I need to get a drip system but I’d worry about overdosing it without knowing why it’s dropping so much. Also, I see people add Kalkwasser to their ATO reservoir. Waiting on a better calcium test kit to arrive but if I don’t need to bring up calcium, would adding just the Red Sea alkalinity supplement to the ATO reservoir be an option?

Thanks in advance!

Alk is also consumed by bacteria, for instance nitrification. If the tank is not fully established, and specifically denitrification is slower than nitrficiation (very common) there will be a netto consumption of alkalinity due to the nitrogen cycle that that may be quite high. Its only when you have quite much corals that you see a KH/CA consumption in 1/1 ratio. In newly established tank and/or tank with not so much stony corals, the ratio is more like 1.3/1 or something like that. So its not strange that KH may be consume more than Calcium. And its not strange to sometimes have a high demand in alk just because of bacterial activity.

If you see an equal decline in Ca and KH some here is suggesting spontaneous precipitation. I would say there is only 2 scenario where spontaneus precipitation/non biological consumption of Ca/KH may occur:
1) If pH is abnormal high, like above 8.3
2) Mg is abnormal low, like below 1800 ppm or so.

If those criteria is not the case I doubt spontaneus precipitation may occur.

Jonas