Can't get my alkalinity above 6.4

[tmantaylor18]

I switched from manually dosing 2 part to a dosing pump about 2 months ago. Before I added the pump I kept my alk pretty steady at around 8-8.5 dkh by manually dosing 12-15 ml of each part at night. My alk has slowly dropped to 6.4 while my calcium has stayed the same at 440ppm. I am up to 28ml of each now and they are being dosed 8 times over the course of a day.

My coral growth has been pretty good but some of the SPS are a little pale. I had to add a fan to my sump around the same time I switched to the dosing pump because of the summer heat. The only other thing that has changed somewhat recently was my switch from LEDs to T5s.

Anyone have a guess to why I cant seem to get my ALK up?

Tank info:

-40 gallon total water volume
-Stocked with mostly SPS

-Calcium 440 (Salifert)
-Alkalinity 6.4 (Salifert - have used two seperate test kits + used the check fluid)
-Magnesium 1330 (Salifert)
-Phosphates 0 (Hanna checker)
-No3 0 (Salifert)

 

[MammothReefer]

Maybe you didn't mix the batch right? Is the volume in your jugs dropping? Do you have the dosers on the correct outlets if you are using a APEX, or AC JR?

 

[smokenax]

I've had bad experiences with salifert.
Switched over to elos and noticed better
Results,Dkh was like 2.0 difference ,salifert
Being lower.

 

[tmantaylor18]

Maybe you didn't mix the batch right? Is the volume in your jugs dropping? Do you have the dosers on the correct outlets if you are using a APEX, or AC JR?

Im using b-ionic 2 part. Im also using a bubble magus doser.

I've had bad experiences with salifert.
Switched over to elos and noticed better
Results,Dkh was like 2.0 difference ,salifert
Being lower.

Hmm, never hear of any issues with salifert. Are you saying they consistently test low? I used two seperate kits + the check solution.

 

[trueblackpercula]

Increase your dosing and test the next day. Keep doing this until you achieve your desired levels. Also alk is driven by the demand of your corals.
Take it slow and have you always used bionic ? Because that stuff is amazing but is very concentrated vs home made two part.

 

[dkeller_nc]

One thing you don't mention is water changes - how often and in what amount. All so-called "2-part" additives will significantly shift the ionic content of seawater over a long period. That's not a problem as long as water changes are performed.

Seawater is an incredibly complex mixture of ions. Substantially shifting the concentration of any of the ionic species from natural seawater content can have unpredictable results.

 

[MammothReefer]

Elos tests typically test lower then Salifert. Get a hanna meter if you are worried. But it really doesn't matter just stick to one test kit if you are getting weird results try another test kit of the same brand. (they do go bad and sometimes you get funky ones), and try to test around the same time whenever you test.

 

[tmantaylor18]

Increase your dosing and test the next day. Keep doing this until you achieve your desired levels. Also alk is driven by the demand of your corals.
Take it slow and have you always used bionic ? Because that stuff is amazing but is very concentrated vs home made two part.

Yeah I've been using it from the start. I'll increase by 5ml today and test

One thing you don't mention is water changes - how often and in what amount. All so-called "2-part" additives will significantly shift the ionic content of seawater over a long period. That's not a problem as long as water changes are performed.

Seawater is an incredibly complex mixture of ions. Substantially shifting the concentration of any of the ionic species from natural seawater content can have unpredictable results.

I do weekly 7 gallon water changes.

Elos tests typically test lower then Salifert. Get a hanna meter if you are worried. But it really doesn't matter just stick to one test kit if you are getting weird results try another test kit of the same brand. (they do go bad and sometimes you get funky ones), and try to test around the same time whenever you test.

I'll take water into my LFS later today. thx for the help

 

[dkeller_nc]

That is odd, then. 7 gallons out of (presumably) about 50 should be more than enough to prevent an ion shift that would really affect your ability to raise alkalinity.

What you might try is something very simple - use sodium bicarbonate from the grocery store. In that way, you know exactly what you're putting in your tank. If you add a quarter to half a teaspoon of it per day for 3 days and your alkalinity isn't around 8 dKH, you've either huge coral growth or there's definitely something wrong with the test kit.

If you want pH buffering with the alkalinity addition, I regularly use kent marine superbuffer (it's just a mixture of sodium bicarb and sodium carbonate).

 

[tmantaylor18]

Im using a salt that has low alkalinity but I dose it to match. I do have a few colonies that are showing a lot of growth lately. I can almost see new growth everyday out of my montipora capricornas.

Would dosing baking soda then become a consistent thing for me to dose?

 

[dkeller_nc]

Im using a salt that has low alkalinity but I dose it to match. I do have a few colonies that are showing a lot of growth lately. I can almost see new growth everyday out of my montipora capricornas.

Would dosing baking soda then become a consistent thing for me to dose?

If you want to, sure. Sodium Bicarb (baking soda) & Sodium Carbonate (washing soda) are the basis for the alkalinity part of 2-part dosing. I believe that Randy Holmes Farley wrote an article on making your own 2-part for Reef Keepers mag that has easy-to-follow instructions in it.

 

[trueblackpercula]

Here is the link
http://www.advancedaquarist.com/2004/4/chemistry