pre-mixed water - how long should it sit?

[Decz]

I have a 5 gallon bucket from home depot that I use to pre-mix water for my 20 gallon tank.

I am having a heck of a time with the salinity levels though. I am following the directions on the bag of salt (1/2 cup salt per gallon of water). I have wanted to do a water change for 5 days now, but just can't get it right.

When I mix the salt in the bucket, the salinity test shows the salt levels to be much higher than anticipated. What I did was just leave it as is for a day, and let the powerhead run in the bucket. I thought that maybe it jsut had to settle.

Anyway, a day or two later, the salinity levels are really low! I assumed that maybe the salt had settled to the bottom and had not mixed into the water. I stired things around, hoping to raise teh salinity, but nothing changed.

I added 1/2 cup of salt, and waited a few hours. I checked again, and teh levels were really high suddenly!

--What am I doing wrong!?!?!?!

--How long does the water need to sit, with a powerhead running, before I should use it?

--Is my brand new "full range specific gravity metre by Seatest" inaccurate?

ahhhhhh!!!!!!!

_Decz

[DEmigh]

Frustrating problem you've got...

The directions that came with my SG tester said that it needed to sit in water for 24 hours to give an accurate reading. Also, sometimes bubbles adhere to the needle and that throws the reading off.

Does your "full range specific gravity metre" depend on either of these factors?

Volumetric mixes of salt to water are approximations at best, 1/2 cup salt per gallon of water depends on many conditions (humidity, temperature, etc.) that the manufacturer (of the salt) can't predict.

I hope this helps, somehow...

Edit: Please don't be offended by this (sometimes it's the really dumb questions that really need to be asked) but... how much water are you losing to evaporation from a 5 gallon bucket each day?

[nevpugh308]

Just a thought I had reading your post, and you say one minute the salinity is low then it's high .... for salinity do you use a dip type or floating type ? If its the dip type meter with swinging arm, are you 100% you got all the air bubbles off the swing arm because I've been caught out with that too (newb) and got false readings. I now tap the arm to make sure 100% all the air bubbles are off.

edit : oops, what he said ^ :)

[Decz]

I'm not really losing any wter to evaporation. Over the entire 5 days (6 now), i've lost a total of maybe 1/8 an inch.

as for the bubbles, well, maybe that's my problem. I thought most were taken care of.... I will tap the arm when i test next and see how it goes.


_Decz