In The Swim Alkalinity Increaser for Spas and Hot Tubs - Raises Alkalinity and Balances pH Levels in Your Spa or Hot Tub Water - 100% Sodium Bicarbonate - 2 Pounds

Does exactly what alkalinity increaser should do...increased my pool's alkalinity.

Absolutely love this product. I purchased this on a regular basis always with great results.

No problems with product or delivery.

A+++++

Better price than buying locally

Cheaper alternative to name brands

This alkalinity increaser is 100 percent sodium bicarbonate, the exact same chemical used in other alkalinity increasers (it is baking soda). As with many other chemicals required for pool maintenance, Amazon has a significant discount over those found at your local pool supply store. This product is about 12-13 percent less, from what I have observed.This product is packaged with an internal bag that is closed with a plastic clip (looks exactly like an oversized clip used on bread bags). This makes it a little difficult to pour out as the bag tends to slip out of the bucket. If you are not careful you could end up with the entire bag in your pool. Once about half of the bag is used, I've found it easier to simply empty the bag into the bucket and discard the bag. The bag tends to slide out more when there is less product left in it and when it's full it's too difficult to lift out of the bucket to invert it to pour it out.There is a dosage chart on the back. The chart goes up to a 50,000-gallon pool size. This is nice, as most charts on pool chemicals stop at a lower size. I have a larger pool so with this chart I can directly read the dosage, saving an extra math step (and a potential source of error).As with all alkalinity increaser, this will slightly raise your pH level. And adding acid to lower the pH can lower the alkalinity, so it can take a little back and forth to get both balanced. My best advice for this is, first, test your pool often and try not to let the levels drift too far outside of the desired range. The further they are out of range, the more difficult it is to get them back. Second, add only one chemical at a time (alkalinity increaser or acid) and leave at least 24 hours between adding them. It can be tempting to add a little extra alkalinity increaser since you will probably have to add acid to lower the pH afterwards, but it is not recommended to do this unless you know exactly what you are doing (if you get the alkalinity too high, you will have to try to lower it). Best to add a little less than needed, wait 24 hours, retest, and add more if needed.Works just as any other alkalinity increaser. The staff at the local pool store recommends pouring the required amount (see the back for dosage recommendations) in one location (i.e., do not "broadcast" it or spread it around the perimeter of the pool). They claim this is the best way to increase the alkalinity without increasing the pH. When adding acid, they told me to do the opposite, broadcast it around the perimeter spreading it out as much as possible. They claim this is the best way to lower the pH without also lowering the alkalinity. I'm not sure about the validity of this since I am not a chemist. However, I do know the workers at the pool store are also not chemists so I am more than mildly suspicious this is either an old wives' tale or anecdotal at best.

Lasted for the full season, great price