Balance of Kalk, ATO and salinity

[dolfan]

OK, so I'm running a 90g tank, total water probably 110g with a small collection of zoes, a large frogspawn and a few medium size SPS corals. First off all my inhabitants are doing well, especially as I have been paying close attention to my CA/ALK/MG levels. CA=420 ALK=10 MG=1320

My dilemma is how to keep my salinity from dropping. I have an ATO setup that I have programmed with my Apex to feed freshwater from my RO into the tank 3 times a day but through a float valve so I never overfill. This has been running like this for about 4 years, zero issues.

Just in the past month or so I have added an automated kalk dispenser, it's a 5 gallon container using a small lift pump that has a valve to allow the kalk to drip in. This is also automated running every 30 minutes for 5 minutes and if the PH is less than 8.25. This has been working great and I have very steady PH. I'm using about 1-1.25g of kalk each day roughly. So I have watched my sump and noticed the overall level in the sump has risen a bit and I have actually turned off the ATO program completely for now.

But I have noticed that my salinity level seems to be dropping a bit, it was typically about 1.025 but I've seen it dropping lately to about 1.023. This is measured with a calibrated refractometer.

I'm not sure what to think about salinity? In theory, I shouldn't be losing the salinity only evaporation of water that I would be replacing through either ATO or the kalk. Any ideas what I should look at to keep the salinity more stable?

 

[MiniQuaid]

The kalk dispenser, is it just the straight dosing liquid or is it mixed into water?


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[MiniQuaid]

Just remember kalk is a solid so that answers my own question lol, so even with the ATO off the salinity is dropping?


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[dolfan]

Kalk dispenser is just clear kalkwasser, probably dripping in about 1-2 ounce in 5 minutes on the half hour as needed. Hope that makes sense.

 

[MiniQuaid]

So you are saying you don’t mix it with water before dosing?


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[dolfan]

Just remember kalk is a solid so that answers my own question lol, so even with the ATO off the salinity is dropping?


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Just to be clear, I use a 5g container that I mix in fresh RO water with several tablespoons of Kalk, mix it for about 5 minutes, then let sit with the program off for at least a couple hours for the solution to settle. Then the program is turned back on to dispense on the half hour. But yes, my ATO has been off for over 10 days or so as I noticed my sump level rising with the kalk and ATO on. So now I just have the kalk solution adding back into the tank.

 

[bzb]

Something seems off here. If it's a 29 gallon sump, and you're generally running 20 gallons in it, you'd have to fill it to the top to get the salinity to drop to 1.023 (full 9 gallons). For your volume of water, you need to add 5 gallons of freshwater to drop the salinity by about 0.001

Any water changes? Maybe take the ATO offline for a couple days and see what happens to your numbers.

Overall, I wouldn't be overly concerned if your water level is clearly higher in the sump.

 

[MiniQuaid]

Something seems off here. If it's a 29 gallon sump, and you're generally running 20 gallons in it, you'd have to fill it to the top to get the salinity to drop to 1.023 (full 9 gallons). For your volume of water, you need to add 5 gallons of freshwater to drop the salinity by about 0.001

Any water changes? Maybe take the ATO offline for a couple days and see what happens to your numbers.

Overall, I wouldn't be overly concerned if your water level is clearly higher in the sump.

There’s the math I was trying to get to lol, this is what I was confused about as well something definitely seems off.


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[enderg60]

Dont use Kalk in your top off water. It makes it rediculously hard to balance how much kalk you need vs what your evaporation rate is(which changes daily).

As said, use a method of dosing that does not involve your top off.

 

[dolfan]

Something seems off here. If it's a 29 gallon sump, and you're generally running 20 gallons in it, you'd have to fill it to the top to get the salinity to drop to 1.023 (full 9 gallons). For your volume of water, you need to add 5 gallons of freshwater to drop the salinity by about 0.001

Any water changes? Maybe take the ATO offline for a couple days and see what happens to your numbers.

Overall, I wouldn't be overly concerned if your water level is clearly higher in the sump.

The sump is 55g size, not a standard 55g glass tank though. My estimate is about 20-25g additional water volume to the 90g display tank.

I already have the ATO turned off for now, so the only additional water is coming from the kalk dispensing at the rate of 1-1.25g per day.

I overall thought is if the only introduction of water is the kalk, then over time why would salinity fall? The salt doesn't evaporate, and I've never considered that it gets consumed? I think it might help if I toke a salinity ready every night for a week to track the numbers.

 

[dolfan]

Dont use Kalk in your top off water. It makes it rediculously hard to balance how much kalk you need vs what your evaporation rate is(which changes daily).

As said, use a method of dosing that does not involve your top off.

My ATO and Kalk are different inputs on different programs, so each is controlled individually.

 

[bzb]

Well, in my experience recently, it appears it can be consumed.

I had a pretty mysterious Magnesium level drop - to the point of me adding a half a jug over the BRS 2-part Magnesium - and that's added back as salt, so...

 

[dolfan]

Well, in my experience recently, it appears it can be consumed.

I had a pretty mysterious Magnesium level drop - to the point of me adding a half a jug over the BRS 2-part Magnesium - and that's added back as salt, so...

My situation would seem to support that some is being consumed. I've started to mix my water change a little on the high side to balance this.

 

[lmm1967]

Salinity doesn't disappear. Are you absolutely positive you didn't mix a low batch when doing a water change? did your ATO run while you were doing a water change or something odd? Water temp always the same when testing salinity?

 

[dolfan]

Salinity doesn't disappear. Are you absolutely positive you didn't mix a low batch when doing a water change? did your ATO run while you were doing a water change or something odd? Water temp always the same when testing salinity?

I note my water changes in Fusion and the last was on 11/21/19 so roughly 6 weeks ago. My ATO only runs at 8am, noon, and 6pm so not thinking that it was running during water change. I've noticed this slight drop over the past 3 weeks or so so no water change has been done during that time.

I think I'm doing to take a salinity reading every night to be able to chart the movement and have more data.

I'm not alarmed but want to figure out what is up before something does go south.

 

[lmm1967]

I'm curious to follow - I don't think I've heard off salinity dropping without some sort of influx of fresh water. Not saying it isn't happening - it's just new to me and I'll be curious about the results.

 

[dolfan]

I'm curious to follow - I don't think I've heard off salinity dropping without some sort of influx of fresh water. Not saying it isn't happening - it's just new to me and I'll be curious about the results.

I agree it goes against anything I've known as well. Maybe I'm smoking something! But better periodic testing and recording will help to see it is truly dropping.