How drastic is a salinity change 1.025 to 1.027

stanleo

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I did my water change yesterday and I checked to make sure the salinity matched before adding the new water. Well today I found an old refractometer and calibrated and the salinty jumped to 1.027. I always keep it at 1.025. How bad is this? How much fresh ro water do I need to add to fix it in a 150 total water volume tank? I did confirm it with my current meter.
 
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Not quite following. When you did the water change yesterday, did the tank water and the new water match when tested with the same refractometer? And now you are using a different device to measure the tank water and have discovered that it is actually higher than you thought?
 

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This is why I wish reefers used the same units as marine biologists.

1.025 sg is 33 ppt. 1.027 is 36 ppt. Thats an 8% increase in salinity. Unlikely to kill anything, but not at all trivial. Most marine animals never encounter either level, living their whole lives in a stable 35 ppt.

However, if you did the same calculation with the sg numbers (1.027 and 1.025) youd come to the conclusion that its a 0.2% change, which would be completely trivial. But its not really an 0.2% change, its an 8% change.

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All quibbling over units aside, I'd just take out a little tank water each day and let the ATO replace it til youre back at 35 ppt.
 
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stanleo

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I used my current meter yesterday to confirm that the tank water and the new water were the same salinity. 1.025. This morning I was cleaning and organizing my fish cupboard and found a old meter. I calibrated and wanted to see if it still worked and it read 1.027. I checked with the same meter I used yesterday and it read the same 1.027
 

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Did you calibrate the first refractometer (it is a refractometer, right?) in between measuring yesterday and today? If you did, then maybe it has been 1.027 for a while.
 

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I did my water change yesterday and I checked to make sure the salinity matched before adding the new water. Well today I found an old refractometer and calibrated and the salinty jumped to 1.027. I always keep it at 1.025. How bad is this? How much fresh ro water do I need to add to fix it in a 150 total water volume tank? I did confirm it with my current meter.
Not the end of the world. Just continue with your weekly water changes at 1.025 and it will come down in a few water changes.
 
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stanleo

stanleo

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This is why I wish reefers used the same units as marine biologists.

1.025 sg is 33 ppt. 1.027 is 36 ppt. Thats an 8% increase in salinity. Unlikely to kill anything, but not at all trivial. Most marine animals never encounter either level, living their whole lives in a stable 35 ppt.

However, if you did the same calculation with the sg numbers (1.027 and 1.025) youd come to the conclusion that its a 0.2% change, which would be completely trivial. But its not really an 0.2% change, its an 8% change.

---

All quibbling over units aside, I'd just take out a little tank water each day and let the ATO replace it til youre back at 35 ppt.
My biggest concern is the starfish. When I researched him, I read that they can't tolerate changes in salinity.

I don't have an ATO, I just check every morning and usually have to add about a liter of fresh ro water I have at the ready every day.
 

Billldg

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That’s not that bad, I wouldn’t worry about it, I keep mine at 1.026, but I got lazy and didn’t calibrate my refractometer and ended up raising my salinity to 1.029 and I brought it back down over a few weeks, didn’t affect my starfish at all.
 
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vetteguy53081

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The .2 change is not harmful However, high salinity is. Gradually bring it down adding RO via water loss/evaporation
 

MERKEY

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Do little water changes like stated above until down to 35. Dont worry yet, however if after you do the changes and if it doesnt change or go up that could be another discussion lol

If your tank is 150 L than it is close to 39 g so take 4 L out at a time and add fresh until the water is back to 35.

Should do ya good :)
 

JEREMY82

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I have starfish in my tank it has swings too,they are all still alive,so wouldnt worry bout it to much,remove a bit of your salt water an fill with ro water,do over the course of a wk and u should be fine
 
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stanleo

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Do little water changes like stated above until down to 35. Dont worry yet, however if after you do the changes and if it doesnt change or go up that could be another discussion lol

If your tank is 150 L than it is close to 39 g so take 4 L out at a time and add fresh until the water is back to 35.

Should do ya good :)
The tank is 150 gallons not liters. The cup I use for top offs is measured in liters that's why I used that unit for the top off.
 
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Gareth elliott

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My concern would be the corresponding alkalinity swing. For point of this example starting alkalinity will be 8.5 on a 100g system. Say tank used .5 alkalinity between water changes. Now the tank drops an additional 8%. Bringing you to 7.36. Now you open a new bucket of salt. And this bucket is at 8.9 instead of 8.5(totally normal difference with just about every brand).

on this example system to go from 33 to 36 via a water change would require a 60g change with water at 38ppm. This 60g water change would be at 10.1 dkh @ 38ppm. When fully mixed the tank would jump from 7.36 to 9.07 dkh.

sorry went math happy
 

MERKEY

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My concern would be the corresponding alkalinity swing. For point of this example starting alkalinity will be 8.5 on a 100g system. Say tank used .5 alkalinity between water changes. Now the tank drops an additional 8%. Bringing you to 7.36. Now you open a new bucket of salt. And this bucket is at 8.9 instead of 8.5(totally normal difference with just about every brand).

on this example system to go from 33 to 36 via a water change would require a 60g change with water at 38ppm. This 60g water change would be at 10.1 dkh @ 38ppm. When fully mixed the tank would jump from 7.36 to 9.07 dkh.

sorry went math happy
Perfectly mathed out :)

This is why slow is better and test test test!

If it was asked I apologize but what is in the tank as of now?
 
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stanleo

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My concern would be the corresponding alkalinity swing. For point of this example starting alkalinity will be 8.5 on a 100g system. Say tank used .5 alkalinity between water changes. Now the tank drops an additional 8%. Bringing you to 7.36. Now you open a new bucket of salt. And this bucket is at 8.9 instead of 8.5(totally normal difference with just about every brand).

on this example system to go from 33 to 36 via a water change would require a 60g change with water at 38ppm. This 60g water change would be at 10.1 dkh @ 38ppm. When fully mixed the tank would jump from 7.36 to 9.07 dkh.

sorry went math happy
Thanks, I will get that tested.
 
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stanleo

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Perfectly mathed out :)

This is why slow is better and test test test!

If it was asked I apologize but what is in the tank as of now?
It wasn't. 1 yellow tang, 5 pajama cardinals, 1 damsel, 1 clown, 1 glass cardinal, long spine black urchin, sand sifting starfish, 2 conchs, 3 emerald crabs, hermits and snails, leather toadstool, hammer, birdsnest sps, GSP, and a bubbletip anemone.
 

foxt

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Agree with everyone else, most likely this is not urgent and you can lower your salinity over time. But I am still not sure about what is going on.

Feel free to just stop me if I am just too lost, but if I understand you correctly, this is what happened:

1. tank at 1.025 yesterday, before water change, measured by refract #1
2. water change done yesterday, makeup water matched to 1.025 with refract #1
3. Found refract #2 today, calibrated it, and discovered tank at 1.027
4. Checked tank with refract #1 (did not recalibrate this refract between today and yesterday), 1.027.

Refract #1 and #2 are in agreement today, and since #2 was calibrated today, we are assuming that #1 is reading correctly today as well as yesterday.

So that means that after your water change yesterday, your tank was at 1.025, and something raised the salinity to 1.027 overnight. Evap loss and/or temp swings will affect salinity, but on 150 gals, wouldn't that need to be a pretty significant change in a short period of time?
 
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