spa water maintence, anyone help?

Question

my hot tub/ spas' chemical balance is off. Does anyone know how and or what chemicals to use to
1.raise the total alkalinity
2. raise the calcium hardness.
this is a 500 gal tub.

Answer 1

Sodium Bicarbonate is used to raise total alkalinity in pools/spas. Calcium Chloride for Calcium Hardness. You must check and adjust pH to 7.2-7.6 after adjusting alkalinity and before Calcium adjustment.

EDIT: I appreciate reb's positive comments, but I disagree, a chloride salt is inconsequential in bromine-treated water. That is to say, HOBr cannot liberate chlorine from chloride, although HOCl will always liberate bromine from bromide.

While its true that baking soda is the best buy, driving around searching for ice melt is a poor idea. It is a deliquescent compound, meaning that once opened, it rapidly (hours) absorbs humidity and turns into a hard block. The most economical way to purchase Calcium Chloride for a 500 gallon spa/hottub is to get a large, sealed pail at a pool store. You can get 96% free-flowing beads instead of 77% flake. And when you put back on the lid, the product stays free-flowing. Sure, you will pay $10-$15 for either 10lbs of good stuff in a re-sealable bucket or the same for a nasty, annoying bag which will turn hard as a brick in a couple days. During the winter, if you are already using lots of ice-melt, go that route. But don't spend $10 in gas and 2 hours finding something that will drive you nuts in the summer! Of course, for some people, the thrill of having "beat the system" is worth all sorts of torment. I have friends who think their discovery that ice-melt is used as calcium hardness increaser qualifies them for the Nobel award for chemistry! After a while, you learn the optimum way. Another point here is that dropping a couple bucks at the mom and pop pool stores ingratiates you with them (it does cost them to do free water testing). When you are having a problem, and with a tub, you will have a problem, its just a matter of time, those folks are good friends to have. Dropping a $10 for some overpriced chemicals, saying thank you and smiling is a good way to save a few hundred down the road.
Baking soda from the supermarket is always the best way to go for a hot tub. For pools, ask your pool store if they stock 50 lb bags. (Don't buy 50lbs for a hot tub!! Also, don't use baking soda as a cleaner in a hot tub, as you will raise the total alkalinity above the level it needs to stay at) Likewise, resist the temptation to use baking soda as a pH increaser in a hot tub (pool is slightly different).

Answer 2

Some comments to the good answer of Ren.

Save money and don't buy these items at the pool store.

Buy generic baking soda at the supermarket or a discount store. All sodium bicarbonate is made by Church & Dwight (Arm & Hammer) and the pricing is dependent upon the lable that gets used.

Calcium chloride is "ice melt" Buy it in any discount store. But one word of caution, if you are using bromine as the spa sanitizer, you could have problems buy adding a chloride salt. Check before going forward with this step.

Answer 3

I USED TO LIVE IN HARROGATE