Water change and tank parameters

[Duncan Tse]

Hey my alk is at 9dkh right now and my water change water is 10dkh. Is there a calculator or formula online that can tell me what my new alk levels would be if I do a 5 gallon water change in a 35 gallon tank?

 

[James M]

The water in the bucket is always going to be different from the DT. There’s no calculators that I know of
It’s kinda hard to say what your new levels will be because there are lots of different salts on the market.

 

[Hemmdog]

Hey my alk is at 9dkh right now and my water change water is 10dkh. Is there a calculator or formula online that can tell me what my new alk levels would be if I do a 5 gallon water change in a 35 gallon tank?

I’m not sure about a calculator, but it should end up being 9.1-9.2.

 

[ScottR]

It’s not going to be a big deal to be honest. Your alk may climb a bit but I’m assuming you’re using the same salt you used originally. Just match salinity and you’ll be ok. Think of water changes as replenishment. Alk can swing 0.5 within a day and it’s completely safe.

 

[Duncan Tse]

The water in the bucket is always going to be different from the DT. There’s no calculators that I know of
It’s kinda hard to say what your new levels will be because there are lots of different salts on the market.

I heard it's better to match your water change with your tank parameters so the swing wouldn't be as great. I lowered my tanks alk to 10 from 9 just to see if it'll have an effect on my sps. IO salt is at 10dkh so just seeing if the swing would be too much.

I’m not sure about a calculator, but it should end up being 9.1-9.2.

Thanks that sounds like not much of a swing. I'll test alk after the water change and see the actual values.

It’s not going to be a big deal to be honest. Your alk may climb a bit but I’m assuming you’re using the same salt you used originally. Just match salinity and you’ll be ok. Think of water changes as replenishment. Alk can swing 0.5 within a day and it’s completely safe.

If I kept doing water changes with a dkh of 10 wouldn't my tank alk slowly creep up to 10 also? I am trying to keep it at a stable 9.

 

[ScottR]

I heard it's better to match your water change with your tank parameters so the swing wouldn't be as great. I lowered my tanks alk to 10 from 9 just to see if it'll have an effect on my sps. IO salt is at 10dkh so just seeing if the swing would be too much.



Thanks that sounds like not much of a swing. I'll test alk after the water change and see the actual values.



If I kept doing water changes with a dkh of 10 wouldn't my tank alk slowly creep up to 10 also? I am trying to keep it at a stable 9.

You’ll need to test your salt. What does it mix at? Your tank will have its alk needs and will use it up accordingly.

 

[nereefpat]

New dKH = (5×10)+(30×9) divided by 35 gallons = 9.14

 

[Duncan Tse]

You’ll need to test your salt. What does it mix at? Your tank will have its alk needs and will use it up accordingly.

Water change water is at 10 dkh while my tank is at 9dkh

New dKH = (5×10)+(30×9) divided by 35 gallons = 9.14

Thanks! Does that mean if I keep doing future water changes my tank water will slowly creep up to 10dkh? I'm dosing 2 part right now and my alk is stable at the moment.