Another AWC post

KonradTO

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Hi all,
I finally got a doser (jebao DP4) for 2 part dosing, since I am manually dosing Alk only at the moment. I have alk decreasing at a rate of 0.3 dKH/day (calcium is quite stable just with water changes) so I decided to start dosing automatically. Since 2 heads will be unused I was thinking to use them for an automatic water change system controlled by both the DP4 and reefpi (taking care of issues with ATO and safety float switches in case of failures).
In the BRS video on saltwater storage () I have seen that the salt I am using (Red sea coral pro ) is actually one of the worsts for this purposes since its high concentration of elements make it prone to precipitation. I am wondering if I should get some more stable salts like TM? Or the RSCP will reach a plateau where will stop precipitating and become more "stable" after few days? In the end the price here in Germany is quite similar for RS and TM.
Is there any other issue with AWC I should consider from the water chemestry POV?
 

Randy Holmes-Farley

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For AWC, high alk mixes can be OK, since you do not need to heat or stir them. I used normal IO this way.

There may be some precipitation of calcium carbonate over the long term, but that's not generally a concern since they often have plenty extra.

That said, using a lower alk mix is certainly a fine plan.
 
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KonradTO

KonradTO

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For AWC, high alk mixes can be OK, since you do not need to heat or stir them. I used normal IO this way.
Thanks for the reply Randy! In the brs video I understood the contrary..don't they say that if there is no heat&circulation the alk drops from 12 to 8 dkh with RSCP?
There may be some precipitation of calcium carbonate over the long term, but that's not generally a concern since they often have plenty extra.

That said, using a lower alk mix is certainly a fine plan.
The decision on high vs low alk salts depends on the nutrient level we want to keep the tank at? If you run ultra low nutrient you want lower Alk and if you have higher N and P you can run higher alk because there is more available for growth as far as I understood from other threads.. Because in my case I have more LPS than SPS so I am guessing that higher alk would not be a problem. Also you need to dose more to keep alk higher compared to low alk salts right? Cause I have a bit lower pH than usual so dosing more often would be a good thing to keep pH up? Or I am risking to have stronger pH swings in this way?

I was also wondering how long should I wait between dosing alk and Ca to avoid interactions.. they form CaCO3 if dosed together right?
 

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Thanks for the reply Randy! In the brs video I understood the contrary..don't they say that if there is no heat&circulation the alk drops from 12 to 8 dkh with RSCP?

All high alk mixes are prone to precipitation. Whether it happens or not may depend on the home air CO2 levels and many other factors, but one member did a very careful study and could not reproduce the precipitation without going to extreme heat:

 

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The decision on high vs low alk salts depends on the nutrient level we want to keep the tank at? If you run ultra low nutrient you want lower Alk and if you have higher N and P you can run higher alk because there is more available for growth as far as I understood from other threads.. Because in my case I have more LPS than SPS so I am guessing that higher alk would not be a problem. Also you need to dose more to keep alk higher compared to low alk salts right? Cause I have a bit lower pH than usual so dosing more often would be a good thing to keep pH up? Or I am risking to have stronger pH swings in this way?

I was also wondering how long should I wait between dosing alk and Ca to avoid interactions.. they form CaCO3 if dosed together right?

I do not think that one needs to keep the tank at the alk level in the new salt water if you use an AWC. That said, the alk/nutrient discussions based on tank levels is basically as I understand it.

Space out the dosing by at least a few minutes for one to mix in before you add the other.

For alk stability, dosing during the day is best. For pH stability, dosing high pH additives at night is best. Alk stability may be more useful.
 
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KonradTO

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I do not think that one needs to keep the tank at the alk level in the new salt water if you use an AWC. That said, the alk/nutrient discussions based on tank levels is basically as I understand it.

Space out the dosing by at least a few minutes for one to mix in before you add the other.

For alk stability, dosing during the day is best. For pH stability, dosing high pH additives at night is best. Alk stability may be more useful.
Great! Thanks for the tips!!!
 

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