SG keeps fluctuating...grrr

[cuteios]

Hi everyone,

 

Well my tank has been up for cycling for around 3 days now and the water is pretty clear. I used a local salt mix for my water and I've noticed that I seem to be getting a bit of a fluctuation on the Specific gravity. When I set it up it was reading at 1.023, then I saw it at 1.025 yesterday morning...so I took out some water and topped off with R/O bottled water. That seemed to fix the problem but when I got up today it was reading at 1.025 again...what gives. The average temp of the water is at 82 degrees....it gets pretty hot but I'm trying to cool it down with a fan.

 

Can anyone please shed some light on the situation? The criters in the tank don't seem to be affected by this, actually I'm noticing a lot of fan worms popping up all over the place. But it's still worrying me a bit.

[caja]

The SG will fluctuate with the temp. Try to get the SG reading at the same time each day.

[Twins Guy]

dude- its called evaporation. with all that heat and fans for cooling you're inevitably evaporating quite alot of water. not salt though. as the water evaporates your salt concentration increases-hence the increased SG. use RO to replace evaporated water, the more frequent the better (daily should suffice).

tg

[Zontar]

When water's cooler it's SG is higher, simply because it is more dense, evaporation is probably playing some role as well. Just keep in mind most hydrometer (the dip kind at least) are calibrated to about 75 degrees.

[cuteios]

oh ok...but I haven't noticed a drop in the water level that would indicate sufficient evaporation to cause SG variance. As for the water temp I haven't been able to drop it below 80F that's already cool considering that ambient temperature around here is approaching the 90F+. So far I've been pretty lucky with the huge fan I've got focused on the tank. But I'm looking at attaching a CPU cooler with a heatsink to the back of the tank...just as soon as I can work out a way to power the thing.