Central Valley SWCG w/ Low CL & High PH...

[aylad]

Hi nomar,

I'm so sorry this thread got overlooked!! I hope you're still around.

I know this is way, way late, but just looking at your numbers, I would say the following:

Check the instructions for your SWCG, but most of them want your CYA to be around 70-80 to make the cell work more efficiently. That alone may help your chlorine output.

When adding acid to lower total alk, it needs to be added all at one time. If you add a little at a time over several occurances, it will lower the pH but not do much for the alk. What you need to to according to these numbers is to either aerate the water or add Borax to raise your pH to7.6-7.8, then add enough muriatic acid to drop the pH back down to NO LOWER THAN 7.0. With this pH drop, your alk will also drop. Then aerate the water so that your pH rises again, but the alk will stay lowered. When the pH gets back up into the mid to high 7's again, then you can add more acid to drop it back down to 7.0, further lowering your alk. It's a ratcheting process and takes a little patience, but it will work. The good news is that pH rises in pools with SWCGs naturally, so hopefully it won't take too long to get the pH back up after the acid additions.

After you're finished with adjusting the pH/alk, then use bleach to shock the pool to get rid of any remaining algae. What is the total gallonage of your pool? And is it vinyl, gunite, plaster.....?

Generally when fighting an algae bloom, it's best to do that with bleach instead of depending on your SWCG to do it--it will wear out your SWCG too early--it's more made for maintaining chlorine than generating large quantities of it all at once. Once you get the alk where you want it, the CYA up higher, and the pool shocked, then you should be able to go back to chlorine maintenance with just the SWCG and be all ready to go for next year!

Janet

[nomar116]

Is running the pump for several hours after adding the acid, as well as my waterfall feature, sufficient to aerate the pool? This has been my strategy but I have not been careful enough about managing PH and have never added anything to increase the PH level so that needs to be addressed.

The pool is between 20,000-25,000 gals and I have added about 6-8 gallons of muriatic acid so far in lowering the TA from about 250 ppm to maybe 180ppm now. Seems like a lot but if my method is flawed I am certainly not surprised!

Also, I have heard mention of using bleach for chlorine/shock. Is there a certain kind of bleach to use?

Thanks for all the help!!

[aylad]

The waterfall feature is an excellent way to aerate the water, as is running the SWCG. I don't know how long it will take to get it back up to the mid to high 7's, but that time will be less and less as your TA comes down. Just check your pH periodically, and when it gets back up to the mid 7's or higher, add more acid to drop the TA a little more. It's a ratcheting process, but it sounds as if you're making some progress if you're already down to 180.

Most of us use bleach to shock the pool, because it is easy to acquire, easy to add, and doesn't add anything else to the pool that will throw your other chemicals off, like other forms of chlorine will. Just plain, unscented, generic bleach. I use WalMart's generic brand, which is 6%. However, keep in mind that when you shock the pool, your pH readings are going to be falsely high, so you need to focus on only the shocking OR the TA lowering, not both at the same time. In a 20,000 gallon pool, 5 gallons of 6% bleach will raise your chlorine to 15 ppm, which is shock level assuming a CYA of 40 ppm. You'll need to get it up to that level, and keep it there by adding enough bleach to get back up to the 15 ppm mark as many times a day as possible. The more consistent you are about maintaining the 15 ppm, the quicker the algae will die off. If you let the chlorine level yo-yo up and down, you're not going to make any progress. In 20,000 gallons, each 2 quarts will raise your chlorine by 1 ppm, so you can use that as a guide to figure out how much to add each time to get back up to 15. You do need to have the pump/filter running 24/7 during this process, and watch your pressure gauge on the filter, cleaning it as necessary. It will also help to brush the pool daily to make sure all the algae is getting exposed to the chlorine. Once the water clears, there is no more algae, and you're not losing more than 1 ppm of chlorine when measuring at night after the sun is off the pool and again in the morning before the sun hits the pool, then you can let the chlorine drift back down to your normal baseline.

So--I would wait awhile on the TA and focus on killing your algae, and once that's done, go back to battle with the TA, but it's your call.

Again, I would check the instructions for your SWCG and see if you don't need to bump your CYA up to the 70-80 range, but don't do it until after your shocking is completed.

What is the finish on your pool? If it's vinyl, then the hardness level is okay, but if it's plaster/gunnite, then you're going to need to raise your calcium levels, too....

Janet

BTW, we LIKE having newbies around--that's why we're here!! We have not ever intentionally "dropped" somebody, and don't find newbies annoying (in most cases, anyway ). Again, sorry this thread got by us, but I'll do everything I can not to let that happen again!

[nomar116]

Janet,

Thanks again. With your help and the help of this forum I've made some good progress. TA is down to an acceptable level and shocking for several days killed most of the algae. Its been about two weeks since I shocked so I need to stir it up and make sure the algae is actually under control.

The pool is a pebble tech gunite finish. Can you walk me through addressing the hardness level to protect the finish of the pool?

Also, once I get the calcium level in check can I reduce the use of the pool pump. What other considerations do I need to keep in mind for the winter? Outside temps are 60-70F during the day and 40-50F at night, sometimes lower. The water temp is presently 45-50F now.

Thanks as always!

[aylad]

I'm pretty sure that Ca should be 200-400 for your pool, but I'm sure someone will correct me if I'm wrong. I gather you're not swimming--I usually cut my pump runtime to 3-4 hours a day during thexwinter, and run it overnite if air temps are supposed to be 29 or lower (only happens a handfull of times during La winters, thankfully!!). Do you plan to close the pool or keep it open for the winter?

Janet