Getting Alk Stable

[mullerjd]

Hi Everyone,

Hoping that others can help me understand how to get my Alk stable.

I have a 60 gallon cube with a total water volume of around 55 gallons. When testing yesterday around noon I got the following:
CA - 400
MG - 1320
ALK - 6.7

I have some Red Sea Reef Foundation A and B that I bought a few weeks ago. Based on the instructions to raise 25 gallons 0.1 dKH it said add 1 ml. I have read not to raise it too quickly so I figured I would just start with 5 ml. Testing again at 8:00 PM the Alk was 8.6. I just retested and the Alk is now at 7.0.

Test kit is a Salifert test kit that is less than a year old. Tank only has a few LPS frags and some zoas and a larger cauliflower colt coral.

I do not have another test kit for Alk but will look to pick one up tomorrow.

Just wondering are the numbers above that I am seeing normal or does it point to an issue with the test kit. I was not expecting the Alk to rise to above 8 by just adding 5 ml.

 

[thegrun]

I suspect either testing error or a bad test kit. Unless you have a lot of coraline algae growing you shouldn't see such big swings with a light stony coral load. My alkalinity would drop about 1.2 dKh if I didn't dose but I have a lot of stony corals.

 

[mullerjd]

I do have a lot of coraline and it grows faster after the 2 urchins eat it but did not think it was a huge amount and the urchins have been in the tank 3 months or so.

I will get another test kit today and compare the results.

One additional question, after dosing the Reef Foundation B how long after can you test to see the affects? I waited 7 or 8 hours the other day and thought that was long enough for it to make it throughout my system since it is only 60 gallons.

 

[JammyBirch]

I suspect either testing error or a bad test kit. Unless you have a lot of coraline algae growing you shouldn't see such big swings with a light stony coral load. My alkalinity would drop about 1.2 dKh if I didn't dose but I have a lot of stony corals.

+1 i struggled with calcium and alk balance in the beginning and found my mag kit was bad. Mag permits the calcium and alk to maintain the levels the reef requires. But i agree with TG you don't have enough load on the system to drop it that low.

Waiting that long to see the effects should be fine, you can calculate it if you know your return pump rate.

 

[Galaxyreef]

Sounds like a bad test kit to me...

 

[jminick2]

this is part of it, tests can vary a lot unfortunately. I use to use red sea alk and hanna. I always found hanna to be the most consistent. However I trusted red sea as well.

 

[mullerjd]

I got a set of Red Sea tests today so will run both and compare the results for CA, ALK and MG to see what they read.

 

[mullerjd]

Ran tests again using both the Salifert and the Red Sea Tests.

Salifert
CA - 400
MG - 1280
Alk 6.1

Red Sea
CA - 380
MG - 1440
Alk - 8.7

Seems like the Red Sea tests would be more accurate since the Salifert test is up and down a lot.

Is there a good way to validate or would I have to bring to my LFS have them test and compare?