How fast to lower salinity for hyposalinty?

[ILikeFish!]

I’m about to start hyposalinity treatment on my 55-gallon tank. I’d like to know how fast I should lower the salinity and how much water to remove daily to reach the target level. My fish aren’t doing to good so the faster the better.

In case it helps my fish are cleaner wrasse, damsel, royal gramma, and fire goby

Additionally, I have a few questions about using praziquantel during hyposalinity treatment. It’s been about 4 weeks of dosing, so I doubt there’s much left in the water. Should I remove any remaining praziquantel before starting the hyposalinity, or is it safe to proceed with both?

 

[OrionN]

I can do a quick calculation if your want to do it in 6 steps, low the salinity of each step by 3.83 ppt instead of 5.75 ppt
6 steps same condition as above
1st 6 gallons result in SG of around 31.2 ppt
2nd 6.8 gal result in SG of around 27.3 ppt
3rd 7.8 gal result in SG of around 23.5 ppt
4th 8.9 gal result in SG of around 19.7 ppt
5th 10.7 gal result in SG of around 15.8 ppt
6th 13.2 gal result in SG of around 12.0 ppt

Hope this help. Best of luck

 

[ILikeFish!]

I can do a quick calculation if your want to do it in 6 steps, low the salinity of each step by 3.83 ppt instead of 5.75 ppt
6 steps same condition as above
1st 6 gallons result in SG of around 31.2 ppt
2nd 6.8 gal result in SG of around 27.3 ppt
3rd 7.8 gal result in SG of around 23.5 ppt
4th 8.9 gal result in SG of around 19.7 ppt
5th 10.7 gal result in SG of around 15.8 ppt
6th 13.2 gal result in SG of around 12.0 ppt

Hope this help. Best of luck

Thank you so much, this is what i was needing.

 

[Jay Hemdal Verified Community Expert]

In a 55 gal tank (total water volume) with current salinity of 35 ppt. You need to low to 12ppt (sg. of 1.009) which is 23ppt need to be remove or 5.75 ppt each removal in 4 steps.
First water change replace 9 gal with RO water water result salinity of ~29.25
Second water change replace 10.8 gal with RO water result salinity of ~23.5
Third water change replace 13.4 gal with RO water resulting in salinity of ~ 17.75
Fourth water change replace 17.7 gal with RO water result in salinity of ~12.

I round of a few digits, so you need to measure salinity as you go along but these are the ball park number if your total volume in 55 gal and the current salinity of 35 ppt

Thanks - the math of the sliding scale always trips me up. Do you know, is there a formula for this? My late father helped me with the math decades ago, but he never had a formula for me to use. I can calculate it step by step, but that is tedious.

One thing though; people don’t need to use RO water for this. Decchlorinated tap water is fine, and has the added benefit of being able to temperature matched to the tank on the fly.

I’ve had people lose fish because they could not produce RO fast enough to get their salinity down in time.

The only need for RO is to limit nutrients for reef systems. If the hypo is being run on a main display, then using RO coming out of hypo is important, but since that is done over many days, RO production is not an issue.

 

[OrionN]

I will think about it and write a formulae for it this weekend.

 

[OrionN]

@Jay Hemdal

Relevant equations posted below
Definition of terms:
Delta Sal = Change in salinity desired
X = Amount of water need to be replace (this value change with each step)
Sal = Salinity of the current water in the tank (this value change with each step)
TV = Total volume of water

If we want to decrease salinity from 35 ppt to 12 ppt in 6 steps then
Delta Sal = 3.8333
Sal = 35 (before the first water change)
TV = 55

Use equation #1 we calculate X
X = 6.024 gal (the first water change volume)

We can use equation #2 to calculate TV of the water after the first change. Let say after the first change we find the salinity is 31 rather than 31.17 as expected. Use equation 2 we find
TV = 52.71 gal instead of 55 gal. Using the new corrected TV will give us accurate X for the rest of the steps.

 

[OrionN]

Just 50+ more posts and I reach 10K club member

 

[Jay Hemdal Verified Community Expert]

@Jay Hemdal

Relevant equations posted below
Definition of terms:
Delta Sal = Change in salinity desired
X = Amount of water need to be replace (this value change with each step)
Sal = Salinity of the current water in the tank (this value change with each step)
TV = Total volume of water

If we want to decrease salinity from 35 ppt to 12 ppt in 6 steps then
Delta Sal = 3.8333
Sal = 35 (before the first water change)
TV = 55

Use equation #1 we calculate X
X = 6.024 gal (the first water change volume)

We can use equation #2 to calculate TV of the water after the first change. Let say after the first change we find the salinity is 31 rather than 31.17 as expected. Use equation 2 we find
TV = 52.71 gal instead of 55 gal. Using the new corrected TV will give us accurate X for the rest of the steps.

Thanks!

My head hurts just looking at this! I'm going to need to sit down and run some trials on this, perhaps after a couple of beers. Can I add this info to my hyposalinity thread?

 

[OrionN]

Of course. You can use it as you can see fit. I cannot type equations well, so I just have to write and take picture of it.

 

[ILikeFish!]

Thanks - the math of the sliding scale always trips me up. Do you know, is there a formula for this? My late father helped me with the math decades ago, but he never had a formula for me to use. I can calculate it step by step, but that is tedious.

One thing though; people don’t need to use RO water for this. Decchlorinated tap water is fine, and has the added benefit of being able to temperature matched to the tank on the fly.

I’ve had people lose fish because they could not produce RO fast enough to get their salinity down in time.

The only need for RO is to limit nutrients for reef systems. If the hypo is being run on a main display, then using RO coming out of hypo is important, but since that is done over many days, RO production is not an issue.

Im actually doing it in my main display, i already removed 6 gallons and put 6 gallons of RO water back in, is that bad?

 

[ILikeFish!]

Of course. You can use it as you can see fit. I cannot type equations well, so I just have to write and take picture of it.

Im actually doing it in my main display, i already removed 6 gallons and put 6 gallons of RO water back in, is that bad?

 

[ILikeFish!]

I wouldn’t worry about prazi, it’s likely gone at this point by bacteria and the water changes lowering the tank would take more out.

Im actually doing it in my main display, i already removed 6 gallons and put 6 gallons of RO water back in, is that bad?

 

[ILikeFish!]

Help

 

[ILikeFish!]

My water is now at 1.020 or 31 ppt

 

[ILikeFish!]

Should i put saltwater back in

 

[ILikeFish!]

Thanks - the math of the sliding scale always trips me up. Do you know, is there a formula for this? My late father helped me with the math decades ago, but he never had a formula for me to use. I can calculate it step by step, but that is tedious.

One thing though; people don’t need to use RO water for this. Decchlorinated tap water is fine, and has the added benefit of being able to temperature matched to the tank on the fly.

I’ve had people lose fish because they could not produce RO fast enough to get their salinity down in time.

The only need for RO is to limit nutrients for reef systems. If the hypo is being run on a main display, then using RO coming out of hypo is important, but since that is done over many days, RO production is not an issue.

Please help

 

[ILikeFish!]

Of course. You can use it as you can see fit. I cannot type equations well, so I just have to write and take picture of it.

Edit im actually at 1.023 i mixed it up

 

[Jay Hemdal Verified Community Expert]

Im actually doing it in my main display, i already removed 6 gallons and put 6 gallons of RO water back in, is that bad?

That’s fine, just go to the next step as outlined by @OrionN

 

[OrionN]

In a 55 gal tank, you likely have less than 55 gal of water. I would use equation #3 to calculate the actual volume you have, then use equation #2 to calculate X for the next water replacement.
Since I calculate everything in term of salinity, it is easier to measure/report salinity instead of Specific Gravity.

 

[ILikeFish!]

That’s fine, just go to the next step as outlined by @OrionN

In a 55 gal tank, you likely have less than 55 gal of water. I would use equation #3 to calculate the actual volume you have, then use equation #2 to calculate X for the next water replacement.
Since I calculate everything in term of salinity, it is easier to measure/report salinity instead of Specific Gravity.

Thank you. i was going to originally going to bring the water down in 6 steps over 36 hours, do i need to bring it down slower since its in my main tank? Also since i was waiting for some help before i did anything I haven’t added any rodi water in like 10-12 hours, is that okay?

 

[OrionN]

Salinity right now?
Estimate total volume?
What is the final salinity you aim for?
6 steps in 36 hrs so 6 water changes each 6 hrs apart.
You can use equation #2 to do the initial water replacement. Then use equitation #3 to calculate the actual water volume.
Then use equation #2 to calculate the rest of the water replacement