Alkalinity during water changes

[Rodolfo Garcia]

Hello everyone, I have a question regarding alkalinity during water changes. My 60 gallon tank runs at a stable 8.6 to 8.8 alkalinity throughout the day and i do a water change weekly. I’ve noticed that the water change water mixes at a low alkalinity and makes my alkalinity drop to 8.1 during water changes. How can i make the alkalinity match? I have tropic marin all for reef and then i also have brs 2 part soda. Should i be adding either of those two to my water change water before adding it to the display tank or should i use something else like baking soda?

 

[Randy Holmes-Farley Verified Community Expert]

Sure, you can boost it, but it may not be necessary. I'd use ordinary baking soda if you do.

How much do you change at a time?

If you change 15% of the tank water at 8.8 dKH with new water at 8.1 dKH, the alk only drops to 8.7 dKH. :)

 

[Rodolfo Garcia]

Sure, you can boost it, but it may not be necessary. I'd use ordinary baking soda if you do.

How much do you change at a time?

If you change 15% of the tank water at 8.8 dKH with new water at 8.1 dKH, the alk only drops to 8.7 dKH. :)

My tank has about a 40 gallon water volume and i change weekly 5 gallons of water.
I guess a better question is, should i be dosing my water change water to match my display tank?
Is there a problem with using tropic marin all for reef or brs soda ash instead of baking soda?

 

[mook1178]

Is your new water at 8.1 or is the tank at 8.1 after the water change?

Either way adding baking soda will get you up to match your tank.

 

[mook1178]

I believe AFR requires bacterial consumption to create the alkalinity, so use the soda ash

 

[Randy Holmes-Farley Verified Community Expert]

My tank has about a 40 gallon water volume and i change weekly 5 gallons of water.
I guess a better question is, should i be dosing my water change water to match my display tank?
Is there a problem with using tropic marin all for reef or brs soda ash instead of baking soda?

Very few people do. I don't, but that's because I do my changes by AWC and there's no need to match anything.

But there is also certainlty nothing wrong with adding a little bit of baking soda to the new salt water to booot alk to match the tank.

 

[Rodolfo Garcia]

My tank has about a 40 gallon water volume and i change weekly 5 gallons of water.
I guess a better question is, should i be dosing my water change water to match my display tank?
Is there a problem with using tropic marin all for reef or brs soda ash instead of baking soda?

Very few people do. I don't, but that's because I do my changes by AWC and there's no need to match anything.

But there is also certainlty nothing wrong with adding a little bit of baking soda to the new salt water to booot alk to match the tank.

Im doing a water change this weekend and if by any chance i do feel the need to dose the water, what is the recommended amount of baking soda to add to the new 5 gallons of water and can i just add the powdered baking soda directly to the new water?

 

[Uncle99]

Hello everyone, I have a question regarding alkalinity during water changes. My 60 gallon tank runs at a stable 8.6 to 8.8 alkalinity throughout the day and i do a water change weekly. I’ve noticed that the water change water mixes at a low alkalinity and makes my alkalinity drop to 8.1 during water changes. How can i make the alkalinity match? I have tropic marin all for reef and then i also have brs 2 part soda. Should i be adding either of those two to my water change water before adding it to the display tank or should i use something else like baking soda?

Not that it’s a big gap but why not just run your Alk at 8.1dkh. Then there’s no variance.
If your new water is 8.1 and the tank runs 8.6-8.8, something must be contributing to that.

 

[Randy Holmes-Farley Verified Community Expert]

Im doing a water change this weekend and if by any chance i do feel the need to dose the water, what is the recommended amount of baking soda to add to the new 5 gallons of water and can i just add the powdered baking soda directly to the new water?

Very little. 0.34 grams (0.07 teaspoons) of baking soda will raise 5 gallons by 0.6 dKH.

Might be easier to dissolve ten times that amount in ro/di (Sat, 100 mL) and then add 1/10th of the liquid.

 

[RobertK]

How big is your SW mixing container? Might be easier to adjust the alk there. You can use this calculator to determine how much baking soda to use.

 

[ReneReef]

Before you start boosting anything:
What salt are you using (brand and type)?
What salinity do you mix your saltwater at?
How do you test salinity and is that meter correctly calibrated?

Because, if you use a salt that mixes to a KH of 8 at 35ppt salinity, but your measurement is off by -10%. Then your freshly made saltwater is 31.5ppt and has a KH of 7.2.

 

[Freenow54]

Give Fritz Hi Alk Salt a try

 

[exnisstech]

I target 8.5 but don't fret as long as it's 8-9 dkH. I use IO purple and have never adjusted fresh water in 10 years. Nothing has ever looked unhappy after a 10 % WC including acros. When i tested fresh saltwater water which isn't often it was around 9 dkH.