Alkalinity

[Neo Jeo]

I’ve had my tank up and running for about a month and for some reason my alkalinity is around 6.7-7.2

I have done three water changes so far . I use coralife salt. Why isn’t it in the 8 to 11 area ?

 

[saltyfilmfolks]

What size tank? What size water changes? What test kit?

 

[Crabs McJones]

When you mix up saltwater how long are you letting it sit before using it?

 

[Neo Jeo]

120G
18% water change
Hanna test kit

Maybe the Hanna? Maybe I’m doing it wrong?

 

[Neo Jeo]

When you mix up saltwater how long are you letting it sit before using it?

When you mix up saltwater how long are you letting it sit before using it?

2 days

 

[lewisriverfisherman]

I would test the salt that you mix up and see what you get? If it's low you might have to dose Alk.

 

[Neo Jeo]

I would test the salt that you mix up and see what you get? If it's low you might have to dose Alk.

Ok, I checked how I’m testing and I’m doing it right. I don’t have that many corals so I don’t understand why it’s low.

 

[mystersyster]

6.7 to 7.2 is fine as long as it's stable. What is your salinty? Do you have a lot of sps and lps?

 

[Crabs McJones]

2 days

Do you notice any precipitation after two days? Are you heating and mixing the water or is it just sitting.

 

[Neo Jeo]

6.7 to 7.2 is fine as long as it's stable. What is your salinty? Do you have a lot of sps and lps?

I thought 8-11 is normal range. My salt lvl is 1.026 . I have a few corals nothing much, I just started

 

[Neo Jeo]

Do you notice any precipitation after two days? Are you heating and mixing the water or is it just sitting.

I’m heating it and mixing. With a lid on.

 

[Randy Holmes-Farley Verified Community Expert]

Alkalinity typically declines in a reef tank, and many people find they need to frequently dose it. many people dose it several times a day.

If the tank was up for a month and the alk declined to 7 dKH, that's normal. Water changes will not, most of the time, be adequate to maintain it.

This has more:

The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION
http://www.reefedition.com/the-many-methods-for-supplementing-calcium-and-alkalinity/

 

[Neo Jeo]

Alkalinity typically declines in a reef tank, and many people find they need to frequently dose it. many people dose it several times a day.

If the tank was up for a month and the alk declined to 7 dKH, that's normal. Water changes will not, most of the time, be adequate to maintain it.

This has more:

The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION
http://www.reefedition.com/the-many-methods-for-supplementing-calcium-and-alkalinity/

Well it looks like I have some reading to do then

 

[Neo Jeo]

@crabs_mcjones what do you do ?

 

[Oberst Oswald]

Don't put your complete trust in the Hanna reagents. I once bought 3 new bottles and did a test with the 3 of them. Two were close but one was far enough off from the other two that I always worry when I get my next new bottle it will show my alk is not what it was.

 

[rkpetersen]

OP, first check your freshly made salt to see what alk is actually going in. If it's on the low side, consider changing salt to something like Red Sea Coral Pro, which consistently mixes up to an alk of 10+. Second, if your alk is lower than the salt you're using and you have few stony corals and clams, the decreased alk in your system is probably due to some undetected abiotic precipitation of calcium carbonate. It can encrust on heaters, pumps, and other warm surfaces. Third, if this is the case, you should consider manual or even better automated 2 part dosing. Or, if you use an auto top off system you could consider trying kalkwasser, although it warrants some respect as it can kill your tank if an accident occurs.

 

[Crabs McJones]

@crabs_mcjones what do you do ?

I would start with checking your saltwater right after you've mixed it as others have said. But I generdally don't let me salt mix sit (even if it has a powerhead and heater) for more than 2 hours.

 

[NS Mike D]

I would start with checking your saltwater right after you've mixed it as others have said. But I generally don't let me salt mix sit (even if it has a powerhead and heater) for more than 2 hours.

some salt directions say to mix the salt for 24 hours before adding to the tank. can you elaborate on this? when I buy salt water from the LFS I presume it was made in advance, day and weeks - are you suggesting this is inferior salt water?

 

[Randy Holmes-Farley Verified Community Expert]

some salt directions say to mix the salt for 24 hours before adding to the tank. can you elaborate on this? when I buy salt water from the LFS I presume it was made in advance, day and weeks - are you suggesting this is inferior salt water?

The concern is that the alkalinity is very high in some salt mixes, and the tendency for abiotic precipitation of calcium carbonate is much higher in raw salt water than in an aquarium. So people often see the alkalinity decline over time, especially if they heat it or mix it with a powerhead that is getting water (calcium carbonate is less soluble at higher temps).

Some people do not see this problem at all, or they do not care as much. Your home air Cow levels alters the pH of the aerated salt water, and pH is a big driver of potential precipitation.

I store my new salt water for a month and used it just fine, but I also wasn't particularly focused on ensuring the alkalinity in it was exactly the same every day.

 

[cracker]

I think the 24 hrs mix is for aerating the water . My Alk always drops if left in the barrel for a while like a day or 2 .