ULNS and Alk

[Danh Ngo]

I’m moving toward ULNS, and I’m a carbon doser. Try to keep phosphate and nitrate nearly undetectable, I want to move on to sps later on. My question is Alk from7-12 is fine for reef tank but for a ULNS and carbon dosing, should I keep Alk at a certain level? Some post said about 7.7 to 8 is good for ULNS.
Also if my Alk is at 9.5, if I want to bring it down, just let coral consume it to the desired level, am I correct on that?
Thank you

 

[Waters]

Yes...with lower nutrients you want to keep your ALK on the low end of the acceptable range. Also correct, to bring it down just let it drop on its own, and make sure whatever salt you use to do your water changes mixes up to a lower number (I use Red Sea Blue which is meant for a ULNS).

 

[reeferfoxx]

Definitely keep alk on the lower end with ULNS. 7-8dkh range is perfect. Yes, letting the dkh naturally fall is a good way to reduce it.

 

[Danh Ngo]

Definitely keep alk on the lower end with ULNS. 7-8dkh range is perfect. Yes, letting the dkh naturally fall is a good way to reduce it.

I use reef crystal, if I dont remeber wrong this salt mix has a really high Alk.

 

[reeferfoxx]

I use reef crystal, if I dont remeber wrong this salt mix has a really high Alk.

Yes it does.

 

[Danh Ngo]

Yes it does.

What is a good way to lower the Kh from the New saltwater?

 

[reeferfoxx]

What is a good way to lower the Kh from the New saltwater?

You can use Muriatic acid to reduce alkalinity. Just purchase it at the hardware store. I think the dose is 0.1mL per gallon. Maybe @Randy Holmes-Farley has the recipe?

 

[Danh Ngo]

I have Seachem Acid Buffer, I think I can use that but no clear instruction on how to lower Alk in saltwater , maybe I have to give it a try with a 1G jugxD

 

[reeferfoxx]

I have Seachem Acid Buffer, I think I can use that but no clear instruction on how to lower Alk in saltwater , maybe I have to give it a try with a 1G jugxD

Does it come with a math equation?

 

[reeferfoxx]

I have Seachem Acid Buffer, I think I can use that but no clear instruction on how to lower Alk in saltwater , maybe I have to give it a try with a 1G jugxD

Actually, after looking at it, it's not the same thing. That would reduce pH. They don't recommend it for saltwater.

 

[Danh Ngo]

Actually, after looking at it, it's not the same thing. That would reduce pH. They don't recommend it for saltwater.

@Randy Holmes-Farley used to mention about using Acid buffer or Muriatic. Seachem acid buffer also convert Alk no Co2 that is the reason PH will drop, as my understand. Aerating the mix after adding Acid buff will help to remove CO2 and bring PH up.

 

[Randy Holmes-Farley Verified Community Expert]

ALL alk reducing methods have a massive pH lowering effect (and the same amount per unit of alk depleted), so this procedure needs to be done very slowly in a display tank, or done in new salt water that gets aerated before use.

Here are typical recipe directions:

Sodium Bisulfate to Reduce Alkalinity in New Salt Water or in Display Tanks
https://www.reef2reef.com/threads/s...in-new-salt-water-or-in-display-tanks.362825/

Muriatic acid:
https://www.reef2reef.com/threads/reducing-alkalinity.339109/#post-4214464

 

[Randy Holmes-Farley Verified Community Expert]

Actually, after looking at it, it's not the same thing. That would reduce pH. They don't recommend it for saltwater.

It will work out to reduce alkalinity (see recipe above), but you can buy the same chemical (sodium bisulfate) from amazon, likely for less anyway..

 

[Danh Ngo]

It will work out to reduce alkalinity (see recipe above), but you can buy the same chemical (sodium bisulfate) from amazon, likely for less anyway..

Thank you Randy, I have a whole new bottle of Seachem Acid buffer. I used it for my freshwater tank before.

 

[Randy Holmes-Farley Verified Community Expert]

Thank you Randy, I have a whole new bottle of Seachem Acid buffer. I used it for my freshwater tank before.

Sounds good.

Good luck!

 

[reeferfoxx]

It will work out to reduce alkalinity (see recipe above), but you can buy the same chemical (sodium bisulfate) from amazon, likely for less anyway..

Edit: nevermind it increases alk.;Facepalm

 

[BigJohnny]

IMO you should keep alk at 7-7.5 if carbon dosing to near undetectable on an average bioload system with Acropora. Just my experience (not with carbon dosing but acros and low nutrients), ran into issues above 8 dkH. Going with the low range of 7-7.5 gives you some room for error while dialing in your new dKH (including test kit inaccuracy/user error during testing).

Dropping from 9.5 to 7.5 is very significant so expect your system to go through some growing pains as the corals acclimate. The possibility of stress and their need for acclimation (even if done very gradually) will result in many changes in your system. Your macro/minor/trace/nutrients will fluctuate due to altered the growth rates of your corals and therefore consumption will need to be closely monitored. The change in dKH/ph alone will likely reduce precipitation and slow the calcification rates of your corals, which will make you need to dose less. Monitor corals for paling as well and reduce lighting if necessary (if only temporary to relieve stress during the transition).

Luckily LPS/Softies are more forgiving so gradually make the change and let the system stabilize before adding acropora. Big changes for acros could possibly translate into stalled growth for months.

Good luck and enjoy

 

[Waters]

Rather than try to reduce ALK in the Reef Crystals, I would just switch salts and do small water changes over time.

 

[Randy Holmes-Farley Verified Community Expert]

Rather than try to reduce ALK in the Reef Crystals, I would just switch salts and do small water changes over time.

FWIW, reducing alkalinity is very cheap and easy. [emoji3]

 

[Waters]

FWIW, reducing alkalinity is very cheap and easy. [emoji3]

I agree....I was just thinking long term costs and extra work (although, like you stated.....it is cheap and easy). Makes more sense (to me anyways lol) to just use a salt that mixes to where you want, rather than worry about changing the ALK every time you mix new salt.