hydrometer

[camm1021]

My hydrometer was reading low and i added more salt water and it didnt move. 90 gallon tank and i added five gallons of saltwater.

 

[abugs1985]

What is the hydrometer reading? You definitely should pick up a refractometer....hydrometers I've always found to be worthless. I'm guessing if you added five more gallons of saltwater your SG is going to be way high. Here is a link to a good quality refractometer... http://www.drsfostersmith.com/produ...&Ntx=mode+matchallpartial&Np=1&pc=1&N=0&Nty=1
Did you give the new salt water time to circulate around your tank before you took another measurment with the hydrometer?

 

[meco65]

Fill the hydrometer with RO/DI water and let it set for 10 or so min. Than try the reading again.

 

[nmprisons]

rinse it really well and make sure there are no debris in it ... but, as abugs said, you need a refractometer.

 

[2swift]

JMHO
Refractometer good one =50$
How much you got invested!
Don't skimp on your tanks life lines!