af normal reef salt question

[stewy14]

I have a 5 gallon bucket of normal ro water, on the back of the af reef salt bucket, it says, for every 390 grams of salt is equivalent to 2.17 gallons
so how many cups would I use? or half cups?
sorry, didn't know where to post this

 

[Formulator]

There isn’t really a universal conversion from weight (grams) to volume (cups) because it depends on the density. But a rough starting point would be about 1/2 cup per gallon. You will need to measure the salinity after mixing and then adjust by adding more salt (raise salinity) or adding more water (lower salinity). Your target is 35 ppt or 1.026 specific gravity. Do you have a refractometer?

You could also get a scale and weigh it per the bucket instructions, but I still recommend measuring and adjusting the final mix as described above.

 

[EricR]

Some (many?) of us just go for 1/2 cup per gallon --> let it mix --> test --> adjust, regardless of which salt we're using.
*my personal opinion is that trying to get more precise initially is more effort than it's worth,,, but that's just me

 

[PharmrJohn]

There isn’t really a universal conversion from weight (grams) to volume (cups) because it depends on the density. But a rough starting point would be about 1/2 cup per gallon. You will need to measure the salinity after mixing and then adjust by adding more salt (raise salinity) or adding more water (lower salinity). Your target is 35 ppt or 1.026 specific gravity. Do you have a refractometer?

You could also get a scale and weigh it per the bucket instructions, but I still recommend measuring and adjusting the final mix as described above.

Pretty much says it all. With my last tank, I would test every single water change batch I made religiously. Mainly to determine whether I made an error with salt mix input. It happened to me a few times where I messed up and had to add either more water or more mix.

 

[stewy14]

I use ~890 grams of salt for 5 gallons, did the math!