Salinity ?

[sefrayser]

I just mixed up a batch of Saltwater for my weekly water change. I am using Instant Ocean. I am using a new bag that I just opened. I am doing a 5 gallon WC so I put 2.5 cups of IO salt. The water is cold(66) and I have a heater in it. I measured the Salinity and got 1.028......With the other bag every time I got 1.025. It has been mixed for about 3 hrs. Could the temp be causing the high reading? Is it the salt? Do I need to let it sit a little longer? If its the salt what can I do to get the salinity down. I was thinking pout some out and add fresh RO then measure and add accordingly. I am about fed up with the IO mix.......calcium low and MG low with the first bag. Now salinity all jacked up.

[StevieT]

So the bucket water is not up to temp yet? What did you use to measure the salinity?

 

If you do have to lower it, depending on how you answer those questions, you just take water out and add fresh RO/DI in to lower the salinity in the bucket

[sefrayser]

No the water is about 66 degrees. It cold here in va. I checked the Salinity with my refractor. I know the calibration is good. Think its the salt?

[paneubert]

No the water is about 66 degrees. It cold here in va. I checked the Salinity with my refractor. I know the calibration is good. Think its the salt?

 

"Temperature is one of the single most important factors influencing accurate refractometer readings and is one of the largest sources of error in measurement. Refractive index is VERY dependent on temperature. It is well known that substantially all materials expand when heated (become less dense) and contract when cooled (become more dense). The speed of light in a liquid increases with temperature, and the refractive index, therefore, decreases."

 

Not my words. But true.

[StevieT]

It could be the temp, let that raise up before you check again. My water starts at about the same temp but I won't test until it is ready

[sefrayser]

Cool, I will let the temp come up to around 78 and then check again. I also want to check the MG and Calcium.

[sefrayser]

I have the water temp at 76.5 and rechecked the salinity with my refractor. It reads 1.027. Thats still high....to me. I know my refrator is calibrated. I like my salinity at 1.025....every batch I mixed with the first bag was that. I have not checked the Mg or Calcium yet. I want to get the Salinity right first. Should I recheck the salinity when the temp gets to 78-79?

[paneubert]

I have the water temp at 76.5 and rechecked the salinity with my refractor. It reads 1.027. Thats still high....to me. I know my refrator is calibrated. I like my salinity at 1.025....every batch I mixed with the first bag was that. I have not checked the Mg or Calcium yet. I want to get the Salinity right first. Should I recheck the salinity when the temp gets to 78-79?

 

I doubt it will change that much since it did not change much versus when it was a lot colder. Probably just a batch of salt that was not quite right. It happens. I know it is annoying, but my method is to add less salt than I think I need and then add small amounts until I am at where I want to be.

 

Could also have been that your 2.5 cups of salt were more than 2.5 if you were not paying perfect attention to the measuring cup being exactly full. Or you had slightly less than your 5 gallons of water. Or a combo of both. I don't know if that would raise salinity that much, but maybe?

[Genj]

What if the meter is ATC?

[bitts]

some one correct me. but is the temp of the refractometer also part of the possible issue. since the water will basically become the temp of the refractometer. then as temp of the refractometer changes doesn't the reading.

[sefrayser]

The refractor was in my house at room temp. The water is the only thing that was cold. The water is up to temp. now and I will check it in the morning.

[Trolldoll]

Mix up the bag or bucket of salt next time. The salt settles and lighter stays up top.

[sefrayser]

Let me ask this. The water in my tank is 1.025, the mixed water for my WC is 1.027. When I do my water change and add the 1.027 will it mess anything up? I have a 34g and will be doing a 5g change.

[ChrisCT]

replace some of the wc water with rodi untill you get 1.025. very simple.

[sefrayser]

Thats what I wil do

[paneubert]

Let me ask this. The water in my tank is 1.025, the mixed water for my WC is 1.027. When I do my water change and add the 1.027 will it mess anything up? I have a 34g and will be doing a 5g change.

 

Math could be done to figure out what salinity you would get out of this combo, but I can tell you from experience that .027 going into .025; 5G of high versus basically 29G of low when old water is taken out will not drastically change thing to the point where your fish float. I mean, you would need to take out 17G of old and add 17G of new to even raise the overall salinity to .026.

 

When I have accidentally done something like this, I just did my water change and then adjusted the whole tank so it was where I wanted it. If I remember when it happened to me, I barely had to replace any tank water with fresh to get mine back where I wanted it. It is always smart to test the water after the change to make sure things went as planned anyway. So that is how I do it.

[paneubert]

Funny story that I think applies to this situation exactly. I had a 5G jug of ".025" water from the local fish store that I keep in my car for emergencies and to keep it out of the way. I just took a sample of it and measured with my refractometer and guess what it read? .030! I let the sample sit in the refractometer for about a minute and it is down to .028 and while I am writing this post it has gone down to.....lets go see......026. So I think I have confirmed the whole "temp messes with refractometer" thing.

[juvance]

Yep, Paul is right. When I test straight tap water for fun (yeah I do that) the reading I get depends on the temperature. When I use warm water I usually get about 1.000 salinity. When I use really cold water, I get nearly 1.004. Not a whole lot of difference, but tap water isn't supposed to have salt I thought. So, it just goes to show that temperature can make the same water have different readings.

[kthehun89]

anybody who cooks can tell you that warm water dissolves more sugar than cold

 

same goes for salinity. that's why it's important to get your WC water to the same temp, then add the salt then test. also, calibrate the refrac. with solution of the same temp as your tank...

[bitts]

I thought that the refractometer was to be calibrated at a specific temp like 68 or something weird. Then there where calculations to be made so as to adjust the readings based on the room temp/actual temp of the refractometer.

 

thus why your suppose to let the the water sit for a bit before reading.