Salt measurements?

Today I mixed new RO/DI water and added 2 and 1/4 cups of Tunze reef salt for every 5 gallons like I did last week. This week I got a reading off of the charts with my deep six hydrometer, but last week 2 and 1/4 cups of salt worked perfectly and got me to 1.024. Im very confused? I could just add more fw to get the salt reading lower, but why is my reading so high this week?

 

Multiple variables have effects on your salinity level. I.E. water temperature, moisture of salt (was it humid in the room the salt was stored? did the salt in the bag/bucket get wet?).

My next thought would be is your hydrometer calibrated correctly and do you have a refractomer?

 

Hmmmm......I dont have a refractometer, but i do need to get one. Everything is the same compared to when I last made my water. I dont let my water sit, I just make it then put it in my tank. This has always worked for me. Should I add fw to the sw bucket or let it sit then measure it...or?

 

Hydrometers are not accurate and the Deep 6 is the worst of the worst IME. I tried one out years ago and it was off by up to .07 and quite variable I've heard lots of other bad reports, so wasn't just that one.

Also, here is a good article that discusses issues with hydrometers.
Chemistry and the Aquarium: Specific Gravity: Oh How Complicated! — Advanced Aquarist's Online Magazine

 

Ok. I will purchase a refractometer soon, and it is sad to hear that the deep six is bad, but for now im stuck with it. I have a tank sitting only 3/4 full now and water that I dont know the salinity reading of...LOL
I tersted my tank water and it gave me a reading of 1.024 while my bucket water was off of the charts. So I think the hydrometer is fine for now,but the bucket water is MUCH colder than the tank water. Last time when I got a reading of 1.024 (Same amount of salt) in the bucket the water was just as cold. What do you suggest I do? MY LFS is closed so I cant get a refractometer now and I need to add water to the tank.

 

As long as the gallons of water are correct and the measurements of salt are correct you should be fine. I would not add cold mixed water if you have animals in the tank.

 

Well the problem is that I used a little more water this ime and was hoping to measure it accordingly so. Ex: 2 and 1/4 gallons of water per 5 gallons then add 1/8 cup until I got to 1.024.....I have only put in about 1 and 1/2 gallons, but I have about 7 gallons of water. I think I need to add more salt, but my reading is 1.031. Ughhhhhhh
I will heat the water with one of my spare heaters.

 

if you can warm the water up in the bucket to roughly the same temp as the water in the tank
then the hydrometer, if its the problem, should then measure the same in both cases (test more than once in case bubbles got trapped thus lifting the swing arm higher)
in which case if it tells you the DT is 1.027 and the water in bucket is 1.027 then IMO your OK
if it gives different readings when both sources of water are the same temp
adjust the water in the bucket to match what it reads in the DT

in emergencies, I have removed a few litres of water from my water change buckets, heated it on the stove , and then returned it to the bucket ( power out situation, when gas stove works but electric is off)

Steve

 

Thanks Steve! Im going to heat the water in the bucket to the same temperature as the tank water then measure my salitnity.

 

Don't know if it's your problem or not, but one issue I've read about and experienced is that during shipping, certain components of the salt mix will settle. If I mix 2 or more batches without stirring the salt in the bag, I too, get random results, even with the same exact measure of salt mix and water. If I do stir the salt, then my mixes are always perfect.