Running a reef tank at 48 salinity

SteveG_inDC

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Everything I've read says the Milwaukee digital refractometer is the most reliable instrument they own for testing salinity, so I trusted mine for months. But then I started getting suspicious. New batches of saltwater (50g bag in 50g of water) were testing low. LFS water that my fish came with tested low. Then I picked up a frag and a fish from two different people in my local club and the water from each guy's tank gave the same low reading of 1.018 SG. Ca and Mg were testing really high (but not Alk), even after water changes. I found an old glass hydrometer, which I've always mistrusted because I figure the paper can move, but it gave a much higher reading than the Milwaukee. I checked and re-checked the procedures I was using with the Milwaukee, cleaning off the well with RO/DI water, calibrating with distilled water, letting the temp adjust, etc.

Well, I just got a new BRS refractometer with test solution and sure enough, I have been running my tank at a salinity of 48 for the past 3 months. The weird thing is that things seem ok. Fish are thriving. My cardinalfish mated and produced eggs (but I think aborted). Fish are eating and growing. Corals are doing ok. Not the best coloration or fast growth, but it's only been a few weeks. Is it possible that running really high salinity is not bad for a reef tank?

Obviously I want to lower it. I guess I can do daily water changes with very low or no salinity water. How slow should I go? 1 PSU/day? I can do the math to figure out how much to change every day at what salinity to achieve this, but is there a calculator?
 
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SteveG_inDC

SteveG_inDC

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Man,I swear I did a search before I posted, but then I found my answer to the question about the calculator.


Looks like for my tank (250g system volume) it will take 93g of fresh water to get it down.

I still wonder about the best rate. I've read that fish can tolerate faster decreases than increases, but what about corals, inverts, bacteria, and microfauna? Should I shoot for 1 ppt/day over two weeks or can I do it faster?
 

davidcalgary29

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Everything I've read says the Milwaukee digital refractometer is the most reliable instrument they own for testing salinity, so I trusted mine for months. But then I started getting suspicious. New batches of saltwater (50g bag in 50g of water) were testing low. LFS water that my fish came with tested low. Then I picked up a frag and a fish from two different people in my local club and the water from each guy's tank gave the same low reading of 1.018 SG. Ca and Mg were testing really high (but not Alk), even after water changes. I found an old glass hydrometer, which I've always mistrusted because I figure the paper can move, but it gave a much higher reading than the Milwaukee. I checked and re-checked the procedures I was using with the Milwaukee, cleaning off the well with RO/DI water, calibrating with distilled water, letting the temp adjust, etc.

Well, I just got a new BRS refractometer with test solution and sure enough, I have been running my tank at a salinity of 48 for the past 3 months. The weird thing is that things seem ok. Fish are thriving. My cardinalfish mated and produced eggs (but I think aborted). Fish are eating and growing. Corals are doing ok. Not the best coloration or fast growth, but it's only been a few weeks. Is it possible that running really high salinity is not bad for a reef tank?

Obviously I want to lower it. I guess I can do daily water changes with very low or no salinity water. How slow should I go? 1 PSU/day? I can do the math to figure out how much to change every day at what salinity to achieve this, but is there a calculator?
All of my softies literally melted when I ran my tanks at 47ppt with a miscalibrated refractometer, and I lost all my snails as well. I didn't have any fish at the time, but the only invert that made it was my Halloween crab. I'm in awe that your tank is thriving at that salinity level! Good for you!
 
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SteveG_inDC

SteveG_inDC

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All of my softies literally melted when I ran my tanks at 47ppt with a miscalibrated refractometer, and I lost all my snails as well. I didn't have any fish at the time, but the only invert that made it was my Halloween crab. I'm in awe that your tank is thriving at that salinity level! Good for you!
Maybe it was because I reached that level slowly over time?
I have tons of snails, xenia and birdsnest are growing. Maybe it's about acclimation. Am planning to reduce slowly, like over 2 weeks, since I'm not in any hurry.
 
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garbled

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I feel like I would want to adjust as slow as possible. You aren't just messing with the salinity, but basically every other element in the tank. Minor, trace, Ca, Alk, the whole lot. If it's not causing an immediate emergency, then maybe like 1 g a day? And keep a sharp eye on Ca/Alk.
 

ItalCanadaReefer

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Everything I've read says the Milwaukee digital refractometer is the most reliable instrument they own for testing salinity, so I trusted mine for months. But then I started getting suspicious. New batches of saltwater (50g bag in 50g of water) were testing low. LFS water that my fish came with tested low. Then I picked up a frag and a fish from two different people in my local club and the water from each guy's tank gave the same low reading of 1.018 SG. Ca and Mg were testing really high (but not Alk), even after water changes. I found an old glass hydrometer, which I've always mistrusted because I figure the paper can move, but it gave a much higher reading than the Milwaukee. I checked and re-checked the procedures I was using with the Milwaukee, cleaning off the well with RO/DI water, calibrating with distilled water, letting the temp adjust, etc.

Well, I just got a new BRS refractometer with test solution and sure enough, I have been running my tank at a salinity of 48 for the past 3 months. The weird thing is that things seem ok. Fish are thriving. My cardinalfish mated and produced eggs (but I think aborted). Fish are eating and growing. Corals are doing ok. Not the best coloration or fast growth, but it's only been a few weeks. Is it possible that running really high salinity is not bad for a reef tank?

Obviously I want to lower it. I guess I can do daily water changes with very low or no salinity water. How slow should I go? 1 PSU/day? I can do the math to figure out how much to change every day at what salinity to achieve this, but is there a calculator?
Just remove some saltwater and add RODI water to replace it. Clearly not too quickly. That will be the easiest way to lower salinity to target levels.
 
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SteveG_inDC

SteveG_inDC

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Just remove some saltwater and add RODI water to replace it. Clearly not too quickly. That will be the easiest way to lower salinity to target levels.
Yes that’s what I’ve been doing. My question was how slowly to go. I was hoping to get some advice from experts on osmolytic dysfunction. A recent paper suggests that high salinity (42 ppt) conveys thermotolerance, which suggests that my main problem with a very saline tank would be the cost of maintaining it. Not sure if there are other consequences for reef organisms or how long they need to acclimate to drops.
 
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SteveG_inDC

SteveG_inDC

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I feel like I would want to adjust as slow as possible. You aren't just messing with the salinity, but basically every other element in the tank. Minor, trace, Ca, Alk, the whole lot. If it's not causing an immediate emergency, then maybe like 1 g a day? And keep a sharp eye on Ca/Alk.
One gal/day would take me 3 months — tedious— but I think 5-10 gals/day may be more doable. Or I may do larger changes of 35 ppt water to supplement smaller changes of RO/DI for tank water.
 
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Randy Holmes-Farley

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Well, I just got a new BRS refractometer with test solution and sure enough, I have been running my tank at a salinity of 48 for the past 3 months.

What does that mean?

48 ppt?
 
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