Calibrating Specific Gravity Test

[Dyngoe]

Hi All,

I have two gravity tests. One is a SeaTes and one is an Instant Ocean. The Seates reads my tank at 1.024 and the IO reads it at 1.028. Now I know these are inacurate compared to an electronic meter, but I was wondering if there was some way to calibrate them. I simply want to make sur my water is as good as I'm guessing.

[giopimentel]

You can use distilled water and it should read 1.000. Be sure to use some warm freshwater on the float valve ones salt can inhibit the movement of the needle. Get a refractometer, its the best bet and they're getting cheaper.

[Dyngoe]

I thought RO water should read 1.000. I'll heat some up to 77F and test it. And, you are right, refractos are getting cheaper. Well worth the investment for all the coral I have.

[djnzlab1]

HI,
I work in a lab and we have to re-cal nearly everything we use a lot. The petstore I bought my simple SPec GRav device the (pet store employee) told me they are only good or accurate a fairly short while and need to be re-checked for accuracy they will check mine for free once a month , I think maybe you are seeing some of that drift that can occur.
I try and rinse mine after use with tap water if you leave salt water in it the salt will build up and concentrate your first reading by adding salt to the equation. we always rinse and then use to get a good zero.
when we take reading in the lab we run Dist h20 if it reads zero it probably oK. we also check a couple standards periodically for accuracy.
Those device that are meters seem to be extremly stable and will last for years if rinsed and handled gently ( not dropped ). The meter only cost a little more than the plastic ones and after you buy two its the same.why didn't i spurge for one.... .
My 2 cents.
Doug