Adjusting the KH of the waterchange

[Smallslandreefer]

I currently have an issue with my water changes. My current salt butch has a KH of 7dkh calcium of 480 and magnesium 1400. My tanks dkh is around 8.5 my calcium is a bit elevated at 490 and my mag around 1450. I do a water change of 50 liters in a 370 liters volume so its about 20%. My problem is this, i try adjusting my kh to meet my tanks dkh so i add aquaforest part 2 pro. I also add part 3 ( the mag) but i dont add part1 calcium since i want to drop my tank levels calcium level. When i adjust the dkh in the waterchange after a few hours it drops again. Why is that? Is it because i am adding it too fast and causes ph spike that cause precipitation? I dont know.. any thoughts and solutions ti keep the dkh at the 8.5 mark before adding that water to tye system?

 

[Reef Psychology]

To clarify, you're not adding equal parts (of a 3 party system) to makeup water and are wondering why dKH is dropping over time? I would think the answer is self-evident - but I could be wrong. As far as I understand it, dosing at different proportions is fine in water that is not balanced, but your salt mix is already balanced and you're unbalancing it. Maybe you should mix your water at the ALK, Cal, Mag proportions you want and dose your tank directly with Component 2+ over time to correct the issue.

 

[Smallslandreefer]

To clarify, you're not adding equal parts (of a 3 party system) to makeup water and are wondering why dKH is dropping over time? I would think the answer is self-evident - but I could be wrong. As far as I understand it, dosing at different proportions is fine in water that is not balanced, but your salt mix already it balanced and you're unbalancing it. Maybe you should mix your water at the ALK, Cal, Mag proportions you want and dose your tank directly with Component 2+ over time to correct the issue.

Actually you dont need to add equal parts of the balling, although my alk and mag dosing is added at the same ml according to the kh dose. My salt mix has 7 dkh and 480 calcium i dint think thats balanced, do you?

 

[Smallslandreefer]

Also the one component that i would assume would drop during the addition of KH is the calcium, which is one of the reasons i didn't add calcium part as my tank has a high calcium level

 

[Reef Psychology]

Actually you dont need to add equal parts of the balling, although my alk and mag dosing is added at the same ml according to the kh dose. My salt mix has 7 dkh and 480 calcium i dint think thats balanced, do you?

No, it isn’t. What brand is your salt, how long and at what temperature are you mixing at?

 

[Smallslandreefer]

No, it isn’t. What brand is your salt, how long and at what temperature are you mixing at?

So the brand is HW marine mix. Which should have higher alk atleast 8.0 however the batch seems to be low on alk. The temperature is usually 25-27 degrees Celsius

 

[Reef Psychology]

Possibly your salt mix could have stratified and needs to be mixed or the temps are too high. I know some salts mix better at lower temperature. I think low pH can also affect ALK too, but I’m not sure by how much or if it would even matter. Could test pH for curiosity sake and take your water to an LFS to get a test comparison.

 

[Smallslandreefer]

Possibly your salt mix could have stratified and needs to be mixed or the temps are too high. I know some salts mix better at lower temperature. I think low pH can also affect ALK too, but I’m not sure by how much or if it would even matter. Could test pH for curiosity sake and take your water to an LFS to get a test comparison.

Yes, forgot to metion is shake every backet of new salt and mix it again before every waterchange

 

[Randy Holmes-Farley]

Raw salt water is extraordinarily prone to precipitation of calcium carbonate due to a lack of organics and phosphate that tend to prevent it. That will lower alk (and calcium, but too small of a change in calcium to see).

I'd use ordinary baking soda to boost the alk in the new salt water, if that is something you want to do. It has a low ph and tends to avoid precipitation.

 

[Randy Holmes-Farley]

My salt mix has 7 dkh and 480 calcium i dint think thats balanced, do you?

Balance is a confusing concept that has different meanings with different definitions, and typically is not especially useful. That aside, 7 dkh and 480 calcium are fine levels for both alk and calcium.

 

[Smallslandreefer]

Raw salt water is extraordinarily prone to precipitation of calcium carbonate due to a lack of organics and phosphate that tend to prevent it. That will lower alk (and calcium, but too small of a change in calcium to see).

I'd use ordinary baking soda to boost the alk in the new salt water, if that is something you want to do. It has a low ph and tends to avoid precipitation.

Excellent thank you. Will the baking soda increase my calcium in any way?

 

[Randy Holmes-Farley]

To clarify, you're not adding equal parts (of a 3 party system) to makeup water and are wondering why dKH is dropping over time? I would think the answer is self-evident - but I could be wrong

It is: precipitation. Higher alk and pH both drive precipitation in raw salt water.

Here's what my normal IO water mixing barrel looked like:

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


Figure 1. The residue on the bottom of the plastic trash can that I use to mix Instant Ocean. I rarely clean it out. The solid is most likely calcium carbonate.

 

[Randy Holmes-Farley]

Excellent thank you. Will the baking soda increase my calcium in any way?

No.