Borates - Why and How
Adding borates can improve your experience with your pool, but is completely optional. If you do plan to use borates, wait until everything else is settled down before adding borates, especially TA and PH. The only situations where we specifically recommend using borates are for pools with a negative edge or other very large water feature creating huge amounts of aeration and for spas using the dichlor and then bleach method. All that said, borates have proven popular with a fair number of people.
- More stable PH
- Helps prevent algae
- Helps prevent scaling in a SWG cell
- Silky water feel
- More sparkle
Like baking soda, borates help stabilize the PH. Unlike baking soda, borates do not also put upward pressure on the PH. Larger quantities of an acid or base are required to make a given PH change with borates as compared to without borates. When your PH tends to drift up, borates don't change the amount of acid you need to use, but they do allow you to add acid less often. They also allow you to lower your TA level more than you could otherwise, reducing the upward pressure on PH.
Borates help prevent algae. Borates won't completely prevent algae from growing, but they do slow down algae growth and make it easier to kill off when you do get algae.
The silky feel and added sparkle are subjective. Not everyone notices these benefits. However, most people do appreciate the change.
- Additional expense
- Concerns about risks to pets
- Not a magical potion to solve all pool woes
In all cases, you should train your pets to not drink from the pool. There are various chemicals in the pool that pose some risk to pets. Dogs that get all of their drinking water from the swimming pool should still not show any symptoms from borates. However, they would be close to the threshold for showing symptoms, rather than 1/100th the level for showing symptoms, as would be required for human safety.
We recommend maintaining borates between 30 and 50 ppm. That normally means raising the borate level to around 50 each spring, so that it will still be above 30 come fall.
Before you start on borates, adjust your TA level toward the low end of the appropriate range for your pool type. See the Recommended Levels chart for appropriate levels. It is easier, and better, to adjust TA before adding borates than it will be after.
There are two approaches to adding borates to the pool: boric acid, or a combination of Borax and muriatic acid. Using boric acid is just slightly more expensive, in most cases, and much easier. Borax and muriatic acid takes more effort and handling that much acid is just slightly risky, but saves just a little money (if you shop carefully).
In either case you can use PoolMath to calculate the quantities required.
Boric acid can be purchased from DudaDiesel and The Chemistry Store. Granular is much easier to work with than powdered. Technical grade is fine.
Boric acid can be distributed across the surface of the pool. Keep the pump running for at least one hour after adding boric acid, and then test the PH and adjust if needed. Boric acid will just slightly lower the PH. Usually the PH change is small enough that no further adjustment is required.
Borax and Muriatic Acid
Borax and muriatic acid can be found at grocery stores and hardware stores respectively. Make sure you double check the strength of the muriatic acid, using half strength acid when you thought it was full strength can lead to problems with PH.
When adding to the pool, you add one gallon of 31.45% muriatic acid, followed by 3 1/2 boxes of Borax, use PoolMath to verify the amount and double check the weight on the box. (For pools smaller than 10,000 gallons it is better to add a half gallon of acid followed by about 1 3/4 boxes of borax each time.) Acid should be poured slowly in front of a return jet with the pump running. Borax can be pre-dissolved in a bucket and then poured slowly in front of a return.
That process is then repeated until you have added the correct total amounts to the pool. The final dose will, of course, be smaller. If you see any undissolved borax, brush the entire pool to help mix it in and get it to dissolve.
24 hours later, test the PH and adjust as needed.
None of the available borate tests are especially precise. Fortunately, the exact level is not critical and just needs to be in the 30 to 50 ppm range. We recommend using LaMotte Insta-Test Borate Test Strips. They aren't great, but they seem to be the best available choice that isn't wildly expensive.