Tank is in its 3rd month of cycle. Have been maintaining salinity of 35 ppm...but today it dropped suddenly to 33.5! I checked all the equipment to see if there was any issue...everything seems to be working fine. Any ideas why salinity would drop that much? No fish or corals yet.
Sudden drop in salinity
- Thread starter Thakki
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Martin Kuhn
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Measurement Error either before or now is the most likely case. Let’s figure out if the reason is human or your tool itself. With which tool and exactly how do you measure your tanks salinity. Do you Check/calibrate it before measuring?
The only other option is that the amount of water in your tank increased a lot but the amount of salt stayed the same.
Is it possible that position of overflows changed? Or can you see another reason that there is more water in your tank system than before?
The only other option is that the amount of water in your tank increased a lot but the amount of salt stayed the same.
Is it possible that position of overflows changed? Or can you see another reason that there is more water in your tank system than before?
Tank size is 100 g.
Has an ATO. Double checked after the drop and working as expected...no issues there.
Have skimmer waste cup draining into a 5 gallon bucket...my first suspicion was skimmer pulling out lot of saltwater out causing drop is salinity...but the bucket was empty...skimmer was working fine.
Before I hooked up my apex, I calibrated with 35 ppm solution that comes with it. Also, just in case I also tested tanks water with my refractometer which is again calibrated with BRS calibration liquid. So probes must be working fine...and this was like 10 days ago.
The only thing I want to do now is test the water with my refractometer and see if it matches with reading on apex probe.
So still the drop is a mystery to me.
Has an ATO. Double checked after the drop and working as expected...no issues there.
Have skimmer waste cup draining into a 5 gallon bucket...my first suspicion was skimmer pulling out lot of saltwater out causing drop is salinity...but the bucket was empty...skimmer was working fine.
Before I hooked up my apex, I calibrated with 35 ppm solution that comes with it. Also, just in case I also tested tanks water with my refractometer which is again calibrated with BRS calibration liquid. So probes must be working fine...and this was like 10 days ago.
The only thing I want to do now is test the water with my refractometer and see if it matches with reading on apex probe.
So still the drop is a mystery to me.
infinite0180
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Ive read bad things about those apex salinity probes. Double check your tanks salinity with a refractometer before doing anything!
Randy Holmes-Farley
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My Tank Thread
The only way salinity can change suddenly is if you add or remove fresh water (by evaporation, ATO running amok, leak that is replaced by ATO, etc.).
madweazl
2500 Club Member
Some subtle things that lead to salinity fluctuations in my tank are:
1) algae/bacteria build up on the weir that leads to a higher water level within the display. Just a slight difference in water level in the display leads to a significant change in salinity due to the surface are of a tank that large.
2) as the macro-algae fill the refugium, they also begin to reduce flow in that weir and result in a higher water level causing the same issue as item one.
Just a couple other things to check.
1) algae/bacteria build up on the weir that leads to a higher water level within the display. Just a slight difference in water level in the display leads to a significant change in salinity due to the surface are of a tank that large.
2) as the macro-algae fill the refugium, they also begin to reduce flow in that weir and result in a higher water level causing the same issue as item one.
Just a couple other things to check.
BestMomEver
2500 Club Member
My refractometer is dead on 1.025. My Apex probe reads over 37ppt all the time. I’ve recalibrated both and I get the same thing. Maddening...Tank size is 100 g.
Has an ATO. Double checked after the drop and working as expected...no issues there.
Have skimmer waste cup draining into a 5 gallon bucket...my first suspicion was skimmer pulling out lot of saltwater out causing drop is salinity...but the bucket was empty...skimmer was working fine.
Before I hooked up my apex, I calibrated with 35 ppm solution that comes with it. Also, just in case I also tested tanks water with my refractometer which is again calibrated with BRS calibration liquid. So probes must be working fine...and this was like 10 days ago.
The only thing I want to do now is test the water with my refractometer and see if it matches with reading on apex probe.
So still the drop is a mystery to me.
Okay...so I tested with my refractometer after calibrating one more time. I read 35 ppm...so most likely the probe is not getting it right. I calibrated it like 10 days ago...and then probe is probably 2 years old...not sure how long they are usually reliable for. Thinking of recalibrating apex probe one more time and see how it goes.
This can happen to the apex probes or any salinity probe if air pockets get into the probe. I occasionally have to shake one of my probes on the nano then it will jump right back up.
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