Mixing Salt

[Jonny967]

I have just purchased an RO unit as i have always purchased my water pre-mixed and have got fed up with all the messing about. Any way i had a go at mixing the salt last night and what a disaster!. I just couldn't get it right, i used 25litre tubs and kept adding a cupful of salt and measuring and after about 8 cups the refractometer still measured 1.015, then i added another and it rocketed to 1.035, so im guessing that the salt was not mixing fast but just settling on the bottom.
I know it will take time to get the correct balance when i can but a measure in and know i will be somewhere near but does anyone know a measurment that will get me near.

 

[Crazy fishes]

Depends on what you mean by 'cup'? It is easier to interchange such data by using weight measurements as opposed to the 'cup' unit. However no one really ever measures the weight of the salt they are adding so it would appear you have to a) get a liter of RO and weight the salt required to get that to the desired S.G then you could use that to multiply to get the amount needed for 10% water changes or the first filling of the tank or b) do what most others do and add little by little of the salt mixing until fully dissolved between each addition.

Good luck with your experiments

Regards

 

[SkiFletch]

As a general rule of thumb Jonny, when figuring out how much salt mix equates to a salinity, start with 1/2 cup per gallon of water and allow mixing for a good hour or two. This will USUALLY dial you in in the 1.021-1.024 range (some salt mixes are different than others), then you can decide how much more to add to go up

 

[Jonny967]

Cheers Ski, i will give it another go. The other problem was getting it into the containers, didn't have a funnel so the floor ended up covered

 

[rabbut]

Salt mixing is about the only part of marine fish I have experience with... Working in the areas busyest LFS supplying RO in my area three days a week, I get to mix salt at least 4 time a week, sometimes more...

IME, salinity can jump about all over the place untill all the salt has disolved. You want to stir the RO vigourusly for a few seconds, to get it going well and then add your salt, in my case 6 fish food tubs for the full water butt vat, so about 1 cup per 5gal, and stir vioourously again. Drop in your air stone or powerhead, which ever you are using for mixing, and leave it alone for about 4-5 hours. Once all the salt has disolved, and the water is clear, take you salinity reading. IME, you need slightly more salt the emptier the box gets, as water start to get to the salt once it's opened, so always add less than you think you need to get the right level. It's easier to add more salt, that take some out If you need to add more, repeat the proceedure as though you are adding to fresh RO, and wait a little longer than before.

HTH
Rabbut

 

[Jonny967]

If i put one cup in five gallons (25 litres) the salinity wouldn't even show much on the Refractometer. I used 5 cupfulls and mixed well last night and left it until about five minutes ago and the salinity is 1.024 with the water nice and clear. Very confussing

 

[rabbut]

I guessing it's just that it hasen't had enough time to finish disolving

All the best
Rabbut

 

[cynos]

Are you using a powerhead or airstone to mix?

 

[cynos]

Are you using a powerhead or airstone to mix?

 

[Dorkhedeos]

I would say the best way is to just keep adding it slowly until you find the specific gravity you are going for. Then just add up all the amounts you added and use that for the next time you mix. Its hard to give specific directions because each salt mix raises the salinity a different amount. I know you need a lot more red sea max to get the salinity to 1.024 than you need the oceanic mix.

 

[BigC]

Buy a cheap set of plastic weighing scales (Argos) to weigh out your salt and re-calibrate your refractometer. Once you weigh out the first couple of times using the scales then you'll hit it about right every time.
Regards
BigC

 

[Dorkhedeos]

The thing with weighing salt is that you have to bring out the scale Moisture gets into salt as well, but I guess thats not such a big deal when you are mixing 5 gallons at a time.