Alkalinity

[NS Mike D]

from instant ocean


Always add the salt mix to the water, not the other way around. Adding water to the salt mix briefly creates a highly concentrated solution that can lead to precipitation of some ingredients. Always allow newly mixed salt water to circulate with a powerhead or airstone at least overnight before use. This allows the carbon dioxide in the aquarium water to reach equilibrium with the carbon dioxide in the atmosphere, which normalizes pH. It also adds oxygen.

 

[slayerhellfire]

Well it looks like I have some reading to do then

I just set up two part dosing my corals look better already, but yeah test your water that you mix, salinity, 2 days of heating it seems like a lot I would do it in one day.

 

[Crabs McJones]

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?

Not suggesting that at all. But I try to use mine right away for the reasons that randy stated. With mine (and it may be something that i'm doing not the salt) if i let it sit to long it starts to precipitate out, so my powerhead i'm using to mix gets covered in a white powder if i go any longer than 2 hours mixing.

 

[Daniel@R2R]

I always try to use my saltwater as soon as possible after mixing. I've found that with RSCP about 30 minutes seems adequate mixing time.

 

[Randy Holmes-Farley]

from instant ocean

Always add the salt mix to the water, not the other way around. Adding water to the salt mix briefly creates a highly concentrated solution that can lead to precipitation of some ingredients. Always allow newly mixed salt water to circulate with a powerhead or airstone at least overnight before use. This allows the carbon dioxide in the aquarium water to reach equilibrium with the carbon dioxide in the atmosphere, which normalizes pH. It also adds oxygen.

We have to be smarter than the companies that supply us. They cannot even agree on directions, and sometimes do not understand chemistry.

Red Sea says this:

"Mix vigorously (without aeration) for 0.5 - 2 hours, until all of the salt is dissolved and pH has stabilized to 8.2-8.4. DO NOT mix for more than 4 hours"

 

[Wam]

In my tank I mix my salt in my sump. I don't recommend it to any one but it works for me. I have a line that is plumed on a float valve from my well to the tank. I take 5gal out and let it fill on its own. Dump 2 cups of salt in the sump and I'm done. Every thing is doing great and I have been doing this for two years. I have a mixed reef and all my coals are thriving. All my water tests are great except my alk it runs at 12-13 a little high but it works.

 

[2Wheelsonly]

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.

I thankfully have not had that issue in the three years iv'e been using it! I noticed the Alk results from the Hanna are always spot on when I do submit samples to professional labs. I look at it as one of the most important tools in my reef tank equipment arsenal.

 

[2Wheelsonly]

We have to be smarter than the companies that supply us. They cannot even agree on directions, and sometimes do not understand chemistry.

Red Sea says this:

"Mix vigorously (without aeration) for 0.5 - 2 hours, until all of the salt is dissolved and pH has stabilized to 8.2-8.4. DO NOT mix for more than 4 hours"

I really don't understand Red Sea's reasoning; once the mixed water goes into our reef isn't it constantly mixed with our flow anyway? An old friend of mine works at Shedd aquarium and he said they basically have a massive mixing station running 24/7 where they mix salt into and constantly keep supply.

 

[Neo Jeo]

I think RedSea is just protecting themselves. I have had friends use RedSea and they lost live stock, couple of people. Maybe it's just another way they can say you did it wrong. Maybe not tho.

 

[Randy Holmes-Farley]

I really don't understand Red Sea's reasoning; once the mixed water goes into our reef isn't it constantly mixed with our flow anyway? An old friend of mine works at Shedd aquarium and he said they basically have a massive mixing station running 24/7 where they mix salt into and constantly keep supply.

They have some chemical misunderstandings, at least in tech support when questioned about these directions, but raw seawater is more prone to precipitation than is normal tank water. The reason is that in a reef tank, a variety of things get onto growing calcium carbonate surfaces and stop the precipitation. These include organics (including even whole bacteria) as well as phosphate. So the same heating and mixing in a reef aquarium does not necessarily cause the same problems as in a bucket of new salt water.

 

[william.sting]

There are a number of good articles that cover the questions you are having that are written by Randy Holmes-Farley a prolific writer about reef aquarium chemistry.

I don't remember if you mentioned your pH. I doubt that the amount of corals you said you have are to blame. And as some have noted, a bit below 8 isn't necessarily a problem. I supplement, by adding calcium and magnesium to my top off water in exact proportions using Randy's two part additive. I take the alkalinity of our water in to account when mixing. My carbonate readings are 8dkh and have been forever.

You should try to keep it at or above 7dkh, so yours is probably not detrimentally low as long as it is stable, which is much more important. You can avoid large swings by doing smaller and more frequent water changes. If you are having trouble keeping it above 7, you are likely having an issue with abiotic precipitation. Check the following:

-Temperature - both for the tank as a whole and for point sources such as a heater or pump
-Magnesium levels (helps prevent abiotic precipitation)
-pH (alters the dissolution constant for -calcium carbonate)
-Calcium level should be within range (Randy has a good article on how to accomplish this)

Lastly, your corals are the final arbiter here. How are they doing? Is their tissue healthy? Are they growing? Are they behaving normally - polyp extension and so forth?

If you decide that you do need to change the parameters of your tank, slow and steady is the key. Rapid changes will kill your corals.

As a starting point in learning about these and other reef aquarium chemistry topics the following article covers some of the basics related to your question:

A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH

By Randy Holmes-Farley

The spam filter won't allow me to send the link, and so you'll have to Google it.

Good luck with your animals!