Salinity level in saltwater tank

[Hetts]

So I just recently setup my BioCube 32 and I premixed my salt into buckets of RO water and I put them into my tank. It’s now been over 24 hours and my salinity has been pretty constant at 1.020 and I’m using a refractometer to check it. I added another 1/2 cup of instant ocean salt to the tank but that didn’t seem to move the salinity up at all. What can I do? I’d like the levels to be at least 1.024. Thanks!

 

[Gernader]

If you kept adding salt with no change in salinity based on a refractometer, you should recalibrate your refractometer with a 35ppt solution

 

[Hetts]

If you kept adding salt with no change in salinity based on a refractometer, you should recalibrate your refractometer with a 35ppt solution

What solution would be at that ppt?

 

[Aclman88]

How much water are you mixing up? 1/2 of salt is used per gallon usually to reach a salinity of 1.025 so if you are only at 1.020 in a 32 gallon system, 1/2 cup might not do that much. I would first ensure your refractometer is calibrated, and then from there I would add about 1/2 cup at a time until you get close. From there, add a little at a time until you reach 1.024 (or whatever your desired salinity is).

 

[Reef.]

Check with RO water that it’s reading 0.

Are you cleaning the refractometer between tests?

You need to add a little then wait for it to mix for a few minutes.

 

[Hetts]

So I just recently setup my BioCube 32 and I premixed my salt into buckets of RO water and I put them into my tank. It’s now been over 24 hours and my salinity has been pretty constant at 1.020 and I’m using a refractometer to check it. I added another 1/2 cup of instant ocean salt to the tank but that didn’t seem to move the salinity up at all. What can I do? I’d like the levels to be at least 1.024. Thanks!

Also, RO water doesn’t need any water conditioner, correct? It’s good to just be directly added into tank with salt?

 

[Aclman88]

What solution would be at that ppt?

I know there are diy recipes but I have always had luck with refractojuice or other calibration solutions you can purchase online form places like marine depot or BRS. Your LFS prob has it as well.

 

[Hetts]

How much water are you mixing up? 1/2 of salt is used per gallon usually to reach a salinity of 1.025 so if you are only at 1.020 in a 32 gallon system, 1/2 cup might not do that much. I would first ensure your refractometer is calibrated, and then from there I would add about 1/2 cup at a time until you get close. From there, add a little at a time until you reach 1.024 (or whatever your desired salinity is).

I mixed 2.5 cups of salt per 5 gallon buckets

 

[Aclman88]

Also, RO water doesn’t need any water conditioner, correct? It’s good to just be directly added into tank with salt?

Correct. As long as your filters are not spent and you are getting true RO water with a TDS reading of 0, it should be fine to add without treatment.

 

[Gernader]

What solution would be at that ppt?

Many refractometer solutions are at that ppt such as BRS calibration fluid. If you cannot get it, then check the salinity with your LFS to make sure.

 

[Aclman88]

I mixed 2.5 cups of salt per 5 gallon buckets

That sounds about right. I would first check that your refractometer is calibrated. If it is, then it just means you need to be adding more salt. As a side note, you should be cleaning your refractometer using your RODI water as tap water will leave residue that could mess around with your readings.

 

[Hetts]

That sounds about right. I would first check that your refractometer is calibrated. If it is, then it just means you need to be adding more salt. As a side note, you should be cleaning your refractometer using your RODI water as tap water will leave residue that could mess around with your readings.

Well I ended up adding 3 cups of salt for every 5 gallons and then when I got it all in my tank I added an extra half cup. When I did 2.5 cups for everything 5 gallons it was 1.020 and when I decided to do the 3 cups it never even changed

 

[Reef.]

Well I ended up adding 3 cups of salt for every 5 gallons and then when I got it all in my tank I added an extra half cup. When I did 2.5 cups for everything 5 gallons it was 1.020 and when I decided to do the 3 cups it never even changed

cups! Heaped cups, level cups...Here’s an easier way 38 grams per litre.

 

[SeanJ]

I added another 1/2 cup of instant ocean salt to the tank

Did you add the 1/2 cup directly to the tank?

 

[Hetts]

Did you add the 1/2 cup directly to the tank?

Yes I did, there is no livestock in the tank

 

[Pntbll687]

Well I ended up adding 3 cups of salt for every 5 gallons and then when I got it all in my tank I added an extra half cup. When I did 2.5 cups for everything 5 gallons it was 1.020 and when I decided to do the 3 cups it never even changed

what salt brand are you using?

Regular purple label Instant Ocean is 1cup will make 2 gallons @ 1.021-22 specific gravity. It even states that on the box. So you may actually need to use more than the "standard" 1 cup per two gallons

 

[Pntbll687]

cups! Heaped cups, level cups...Here’s an easier way 38 grams per litre.

Grams???? Litres???

I'm american, I use FREEDOM UNITS!! Pounds, ounces, gallons, quarts, pints.

 

[Hetts]

what salt brand are you using?

Regular purple label Instant Ocean is 1cup will make 2 gallons @ 1.021-22 specific gravity. It even states that on the box. So you may actually need to use more than the "standard" 1 cup per two gallons

I ended up figuring it out. The refractometer I had apparently is in European units for some reason and not even used to measure salinity of water. So I was getting false readings. I took my refractometer and water to LFS and they tested it at 1.030 so way high and I ended up buying their refractometer which was identical to mine just in US units and for water lol took out 5 gallons of salt water put in 5 gallons of RO water and I’m at 1.025 now

 

[Randy Holmes-Farley]

I ended up figuring it out. The refractometer I had apparently is in European units for some reason and not even used to measure salinity of water. So I was getting false readings. I took my refractometer and water to LFS and they tested it at 1.030 so way high and I ended up buying their refractometer which was identical to mine just in US units and for water lol took out 5 gallons of salt water put in 5 gallons of RO water and I’m at 1.025 now

European units? Europeans measure salinity the same as us. lol

Might be a problem refractometer for many reasons, and might not be for salinity of seawater for sure. But not because its European. lol

 

[Billdogg]

European units? Europeans measure salinity the same as us. lol

Might be a problem refractometer for many reasons, and might not be for salinity of seawater for sure. But not because its European. lol

^^^What Randy said!!!^^^

FWIW - you should calibrate your refractometer using a solution that is at 35ppt (1.026) and NOT RODI water. I use Pinpoint calibration fluid. It's inexpensive and if properly stored will last a very long time. Whenever you calibrate an instrument you will get the most accurate end result using a known source that is as close as possible to your desired end point as possible.

Also - no more mixing salt directly in the tank! Once you have living creatures in there adding dry salt directly to the water can really irritate most of them. That's the reason about 99% of us have a dedicated mixing barrel somewhere around the house! Mine is a 55g barrel that I've used for 30+ years now. It takes ~ 1 50g bag of IO or IORC + 6 cups to = 1.025 for me.