Alk drop

[JWhitener]

Alk question.

Last week my Alk was at 8.7. I went on vacation for 5 days and came back to it being at 7.8. My tank sitter only added frozen food daily. I’m not dosing anything at this time. I have a small amount of LPS corals in my tank. I did a water change last night and today the Alk was still at 7.8. Should I look at doing a 2 part dose if it continues to drop? Not sure what to do exactly.

 

[Uncle99]

Depends on what Alk number your looking to keep.
If it’s 8.7dkh and you want to keep this you’ll need to add back .2dkh per day to maintain that level.

Assuming your drop is consistent.

 

[blasterman]

No to two part. I will guarantee your calcium is fine with that coral load.

Alk on the other hand is depleted by a wide array of biological process in your tank. So, its quite common to have it dive without coral consuming it or calcium moving.

Your choices are to either use water changes to rely on fresh salt mix to bring up alk or dose alk by itself. I prefer the later because its a lot easier and less wasteful.

Alk is just baking soda, and the online reef calculator and a teaspoon is all thats required. I would target dKH of 9 for your tank.

 

[JWhitener]

No to two part. I will guarantee your calcium is fine with that coral load.

Alk on the other hand is depleted by a wide array of biological process in your tank. So, its quite common to have it dive without coral consuming it or calcium moving.

Your choices are to either use water changes to rely on fresh salt mix to bring up alk or dose alk by itself. I prefer the later because its a lot easier and less wasteful.

Alk is just baking soda, and the online reef calculator and a teaspoon is all thats required. I would target dKH of 9 for your tank.

So can I use just the Alk part of a 2 part dosing system to raise the Alk or is it better to use baking soda?

 

[arking_mark]

No to two part. I will guarantee your calcium is fine with that coral load.

Alk on the other hand is depleted by a wide array of biological process in your tank. So, its quite common to have it dive without coral consuming it or calcium moving.

Your choices are to either use water changes to rely on fresh salt mix to bring up alk or dose alk by itself. I prefer the later because its a lot easier and less wasteful.

Alk is just baking soda, and the online reef calculator and a teaspoon is all thats required. I would target dKH of 9 for your tank.

This is counter to current understanding of Alk/Ca...

How to balance Ca/Alk in the reef aquarium?

After reading: http://www.reefkeeping.com/issues/2004-12/rhf/ Here are my takeaways: For most practical purposes, Ca and Alk are consumed equally. However, "...the demand for calcium and alkalinity may not be precisely balanced at 20 ppm calcium per 1 meq/l of alkalinity..." The biggest...

www.reef2reef.com

 

[Randy Holmes-Farley Verified Community Expert]

I agree it depends on your alk goal. When it drops below where you want it, add both parts of a two part unless calcium is already too high (just OK means to dose that part, since it will hardly rise at all for that small alk need).

 

[Randy Holmes-Farley Verified Community Expert]

So can I use just the Alk part of a 2 part dosing system to raise the Alk or is it better to use baking soda?

Use both parts. That calcium change is small going down and small going up.

 

[JWhitener]

Use both parts. That calcium change is small going down and small going up.

So I dosed the 2 part today and the Alk went from 7.8 to 8.2 and the calcium went from 440 to 460. Should I maybe only dose Alk next time since I don’t want my calcium to rise anymore?

 

[arking_mark]

So I dosed the 2 part today and the Alk went from 7.8 to 8.2 and the calcium went from 440 to 460. Should I maybe only dose Alk next time since I don’t want my calcium to rise anymore?

Test your Ca again. You'll probably find it quite different than your last measurement. These test kits are prone to error and inaccuracies.

2.8 dKH = 50 ppm calcium carbonate equivalents. So .4dKH will be roughly 7ppm of balanced Ca. This is well in the error range of hobbiest test kits.

 

[Randy Holmes-Farley Verified Community Expert]

So I dosed the 2 part today and the Alk went from 7.8 to 8.2 and the calcium went from 440 to 460. Should I maybe only dose Alk next time since I don’t want my calcium to rise anymore?

Stick to equal parts dosing unless calcium is already too high.

As mentioned, calcium testing is not precise and accurate enough to jigger dosing on a day to day basis.