Salinity on the rise

SO!! This will be week 3 of the sump being in service and I have been noticing some things that have me concerned..

All I have been doing is adding RO water for top offs every morning and dosing a little here and there to keep levels par. I usually keep my salinity at 1.026-7 but this morning when i went to top off, it was at 1.030...of course I immediately corrected it and now its at 1.025. Does anyone have an idea why it's doing this? The only thing that has been going into the tank has been fresh water (RO), nothing salty. What gives!?

I top off about 3/4 of a gallon every morning.

 

using a refractometer or hydrometer to measure salinity?
if a refractometer, is it calibrated?

 

yep i use a refractometer. I checked it with RO water this morning too, came out 1.000

 

I use a refractometer with ATC also and I notice that if you put only 1 drop and close it if there are any air bubbles you will get a different reading than if you put 2 or 3 drops with no air bubbles. I have that cheap $50.00 one. Does anyone calibrate these with a solution instead of RO water.
Adam

 

I don't know if its your refractometer but maybe the sump is adding more surface area for evaporation so there is more evaporation.

just an idea

 

well i always top off to the same point in my sump...things don't add up in my head, unless i'm missing something?

 

ermano, are you supplementing MgCl2 or MgSO4, or others? That could cause a trend towards higer salinity. When was the last W/C?

 

I dosed with MgSO4 (epsom salt) last week and I did a w/c maybe 2-3 weeks ago...I thought adding MgSO4 or MgCl2 wouldn't have that much of an effect on salinity?

 

Any "salt" supplement will cause salinity to rise, for lack of a better term you test salinity but also specific gravity and MgSO4 or MgCl2 will affect that. How much MgSO4 do you use?
As far as how much it would affect the SG depends of course on how much you add. Whats your Mg level and whats the target level ermano?

 

Mg was at 1350, I like it around 1400 so i added about 2oz of epsom salt, thus raising it 50ppm...would this much have an affect on salinity?

Thanks doc!!