Help with salinity in new tank

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Lavey29

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Greetings everyone, I am new to reef tanks and just finished my second water change on the tank which is a month old and quick cycled with live rock and sand and Dr. Tims. There are 2 fish in the tank. My tank salinity was 1.026 and I changed out 10 gallon of water which was pre mixed and heated 24 hours i advance. I zeroed my refractometer and checked the new water and it was 1.026. I changed out the 10 gallons and now my salinity in the tank reads 1.022 / 3. I am wondering why the level dropped? I know my new skimmer has been running pretty wet with about 1/2 cup of water every day or two. Over a 2 week period will that change my salinity level? it is being replaced with my ATO which is RODI water and I know the salt is supposed to remain in the tank during evaporation. Is the cup from the skimmer causing the fluctuation?

Thanks for any help in advance.....I certainly need it.
 
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Lavey29

Lavey29

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I may have figured out my problem. I mixed the water outside at the mild temperature in my garage and took my reading after it mixed for about 2 hours. I should have taken my salinity reading after the water was warmed up to 78 because the total salinity will vary depending on water temp also. Warmer water lowers the salinity number so my 1.026 probably became 1.022 after it reached 78 degrees which is why my tank is now reading lower level of salinity.

Does this seem like the correct assessment?
 

Suohhen

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Some refractometers auto correct for temperature so if your's isn't that type it would make sense that the skimmer plus a slight error in water change salinity added up to a 3 point drop but you don't state the total water volume so I can't say for sure.
One recommendation for mixing salt is to find out what volume of salt is needed to reach your desired salinity and then use a measuring cup for every future change. This adds redundancy and avoids issues whereby the refractometer may not read correctly due to temp or incomplete mixing. It generally doesn't take long but depending on the salt and its condition it can take a while to dissolve.
 
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Lavey29

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Some refractometers auto correct for temperature so if your's isn't that type it would make sense that the skimmer plus a slight error in water change salinity added up to a 3 point drop but you don't state the total water volume so I can't say for sure.
One recommendation for mixing salt is to find out what volume of salt is needed to reach your desired salinity and then use a measuring cup for every future change. This adds redundancy and avoids issues whereby the refractometer may not read correctly due to temp or incomplete mixing. It generally doesn't take long but depending on the salt and its condition it can take a while to dissolve.


Thanks for the reply. I did use a measuring cup and the same 10 gallons that I did with the first water change. Basically 5 cups of Red Sea salt for the 10 gallons put me right in the range I needed. I leave a little room in case i need to add some RODI if the reading is to high. If it is to low then add a little more salt of course. my refractometer does change with temp so I have to zero it out before each use.
 
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Lavey29

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Could you explain your process for Zeroing out the refract?

The instructions said to use a drop of RODI water to zero. If it is off then you adjust the setting with a small screw driver. I now see that there some stuff called calibration fluid that might be a better method to use.
 

Suohhen

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Yeah for sure it is better to calibrate with something closer to your salinity as you can be a few points off with rodi. This is different tho than temp. The rodi is likely room temp. Regardless the thing to do with a refractometer, especially non ATC is flush the water over the glass for a bit to warm up the glass, or the water. It is not only the thing your testing but the refractometer itself gets cold.
Better yet read what the Grand Master of reefing chemistry has to say on the matter including how you can make your own solution out of table salt.
 

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I had the same issues... easy fix tho ! 1st 0 refractometer with rodi then use calibration fluid, adjust if needed to 35ppm ! That’s each n every time u do a test!!
 
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Lavey29

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Yeah for sure it is better to calibrate with something closer to your salinity as you can be a few points off with rodi. This is different tho than temp. The rodi is likely room temp. Regardless the thing to do with a refractometer, especially non ATC is flush the water over the glass for a bit to warm up the glass, or the water. It is not only the thing your testing but the refractometer itself gets cold.
Better yet read what the Grand Master of reefing chemistry has to say on the matter including how you can make your own solution out of table salt.

Great article, I kind of figured the cheap refractometer might be a weak link. I going to get some calibration fluid and double check the 0 on it at the right temp.
 
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Lavey29

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So I set 0 with the calibration fluid and my tank salinity is worse then before. It's 1.021 now so I will do a small water change tomorrow and start to bring it into the correct range. Luckily I have no corals yet. Hopefully my clowns will be ok.
 

Suohhen

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Fish are totally fine in at that salinity. Coral would not necessarily die in that salinity either but you definitely should get it back up to be safe.
 
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Fish are totally fine in at that salinity. Coral would not necessarily die in that salinity either but you definitely should get it back up to be safe.

I'm doing another small water change today to bring it up a little. I figure for the future if it fluctuates again somehow I can always turn the ATO off and add saltwater by hand instead of RODI for evaporation to stabilize it right?
 
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Fish are totally fine in at that salinity. Coral would not necessarily die in that salinity either but you definitely should get it back up to be safe.

I just ordered a decent digital refractometer from Milwaukie Instruments too. Figure I could double check my readings and hopefully they are even or close to the same number. Fish seem ok so far. Thanks for your thorough responses and help.
 

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I'm doing another small water change today to bring it up a little. I figure for the future if it fluctuates again somehow I can always turn the ATO off and add saltwater by hand instead of RODI for evaporation to stabilize it right?
For sure you can top off with saltwater rather than the water change route, the same principles apply however take it slow. If you can drip the water in that would be best.
 
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For sure you can top off with saltwater rather than the water change route, the same principles apply however take it slow. If you can drip the water in that would be best.

I've dialed back my skimmer so no water is filling the cup. There is virtually no foam just boiling bubbles anyway so I'm guessing there is hardly any waste in the water with only 2 fish. Did 8 gallon water change and salinity is at 1.023 now so came up a little. I will unplug the ATO for several days and just top off with saltwater until I get back to 1.025....thanks
 

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Ah yeah sorry I forgot about the skimmer. Everyone knows that skimmers can take a while to break in but sometimes any change can take a few days to see results. The other thing about skimmers is that they can't handle changes in water level. If their is anything that is causing the water level to rise even momentarily the skimmer can overflow.
 
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Ah yeah sorry I forgot about the skimmer. Everyone knows that skimmers can take a while to break in but sometimes any change can take a few days to see results. The other thing about skimmers is that they can't handle changes in water level. If their is anything that is causing the water level to rise even momentarily the skimmer can overflow.

Yes, I'm new but have already experienced what you mentioned. I shut it off during water changes so I don't get overflow in the sump. It's an oversized skimmer for my tank which is not a bad thing necessarily but it just appears to have not much waste to work with presently hence no foam at the top really just mainly boiling type bubbles. I get a little skim waste out of it though. I just dont want to be emptying decent salt water out of the cup daily and diluting my tank salinity again.
 
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