Need help-High Cya, calcium, and algae

I am new to learning about pools and am trying to get the constant algae out of my pool. Last weak in trying to learn about my pool I found the PS website and learned just enough to be dangerous. My ph was 6.8 and my TA was about 60. My pool is about 20k gallons. Anyway, I started adding borax to get the ph up and kept watching the TA to make sure it was okay. After adding 16 lbs. of borax over a couple of days, the ph went to 7.2 and the TA to 80. I started using bleach and kept using the trichor tabs I already had.

After more reading, I realized my test kit was probably too old and did not have reliable readings. I got a new kit and tested to find the ph at 7.2, fc at .5, TC at 1.0, TA at 150, Calcium was over 500 (stopped adding drops thinking I was doing something wrong), and CYA is way high- not even close to the first mark.

I took the trichor tabs out and dumped in 5 lbs. of 55% chlorine shock. What should I do next? I figure I need to get the CYA level down and the CH down as well while keeping chlorine levels high to get rid of the algea (not sure about the stained walls)

I have a sand filter by the way which has low pressure and low flow. After reading on this site, I now think the impeller on the pump must have some blockage.

Thanks for your help,

Greg

Hi, Greg,

It appears you've got a good grasp of your issues...here's what I would do.

1. Fix the pump....the pool needs a good pump just like we need good hearts.

2. Simultaneously with fixing the pump, I'd get a bunch of Cl in there. Tell us what kind of pool you have before we recommend a dosage.

3. The best fix for a pool with the CYA and CH that high is to drain at least half of it and refill. Test and be prepared to drain half again. That should get your CH and CYA down to manageable levels.

Good work on the pH. As I said, you've got the idea...you just need a plan of attack.

I have an in ground concrete pool. I guess that is a plaster pool?

What about that brown stain I can't get off the walls? Is that a form of algae that can be removed without redoing the walls of the pool? If it is permanent, I would just as soon drain the whole pool and fix everything at once.

Thanks,

Greg

Well, from this distance, it's pretty hard to tell what that stain is.

I agree with draining the whole pool ,clearing the stain and starting with new water. That'll be your simplest, possibly least expensive path.

Turbo,
The stains on the plaster could be a result of a number of things... I know some minor staining I had cleared up after a couple times of shocking the pool water and minor brushing. That was from decaying leaves, etc over the winter months and not from algea. Depending on the cause of the stain some sort of scale/stain remover may work. If you are going to drain the pool then you could acid wash the plaster to remove staining. If it isn't that bad I would see if it clears up this season with chlorine and brushing and then if not explore more intensive fixes in the fall.

Thanks for the help everyone. CYA is about 160. I guess draining the pool all the way and scrubbing the sides might be the ticket. I haven't had a chance to research acid washing the sides. What chemicals should be used and what is the best plan of action? Should I consider refinishing the sides?

One last question. I have some leftover sodium dichloro-****. Does this have any stabilizer in it? I know the trichloro does but not aware of the dichloro. I definitely don't want to put any more CYA in the pool unless I have to.

Thanks,

Greg

dichlor is the other stabilized chlorine, your non stabilzied chlorines are sodium hypochlorite (good old bleach!), cal hypo, and lithium hypochlorite (expens$ive stuff!)

I assume acid washing is done with muriatic acid. What mixture do you use and what effect does this have on the bottom of the pool while washing?

Greg

I drained the pool and it appears that the stains are not really stains. I think it is yellow algae that is growing in the crevices and round pocket holes you can't reach. Even so, I tried applying ascorbic acid and then scrubbing it to no avail. If anything, it bleached the area some from the natural white wall color (looks a little greyer to me).

I would then assume that once I get the pool full again with the correct ph, TA, CH, and CYA, I can keep the chlorine levels up to get rid of the algae.

Greg

Greg,

Your assumption is correct. It will probably take some persistence to eliminate that yellow algae but consistent high levels of Cl and frequent brushing will do the trick.

Yellow algae is frequently misdiagnosed. Google the term and you will find some pictures to help you confirm.

The pool is nearly full (3 or 4 inches to go) and I did some testing. Ph is 7.4, cl is 0, TA is 150 and CYA is 70 - 80, probably 80 (not sure about seeing the dot). If I understand correctly, I need to aerate if possible to get the TA down. I am going to start shocking and will look at the chart to see what I need. I was hoping CYA would have dropped further. I must have drained 3/4 of the pool.

I guess I will just run high cl for now. Any suggestions?

Greg

Hi, Greg,

For a plaster pool and CYA of 80, I'd put in enough Cl to get to 30ppm.

You'll surely get to breakpoint and clean up any "bugs" that may try to establish themselves.

If you have mustard algae, you can maintain that shock level for a few days, brush frequently and run your pump 24/7. Pooldoc advises that mustard algae takes high Cl and a lot of persistence.

After that "shock", you can let your Cl drop on down to 5-10ppm and keep it in that range the rest of the Summer.

30 ppm sounds like a good plan. I put in 10.5 gallons of 6% bleach last night at about 12. At 7 this morning it was all gone. Maybe it left so quick because I tried to scrub a section of the wall with ascorbic acid when the pool was low but I didn't think there was that much that stayed in the pool. Maybe so. I guess that combined with the algae did it. I put more chlorine in this morning (4.2 gallons which is all I had). I will buy some more on the way home and get the ppm up to 30. When will the chlorine level stop dropping so much?

Should I try some ph minus to get my TA down or just hope my little bit of aeration does the trick? I am going to buy a jet that will shoot the water in the air hopefully to improve my aeration ability.

Greg

Hi, Greg,

I would focus on the Cl level for now. Your TA is not at all dangerously high and I would "fine tune" that issue later.

You still have a bunch of organics in that pool and chlorine is your answer. Get a bunch of it and keep bringing it up to 30ppm as much as three times a day if you can. It may take a few days, but your Chlorine will start to hold more and more. Your water will be crystal clear and then you can start to fine tune that Alk.

PS - I believe it was the algae that ate your chlorine...not the acid.

I have no way of telling how high the CL is but I kept dumping in cl to keep it high for 3 days (before putting in 3.5 gallons each day of bleach it looked way darker than 5ppm). The water is clear and I put some 14 lbs. of dry acid in and have the TA down to 130ppm (put in 4 lbs. of borax to bring ph to 7.2). After the chlorine drops I will put in a little more and get it to about 100ppm.

Anyway, I noticed that the sides have a very light green granular looking growth over most of the pool and it won't scrub off. When I vacuum it looks like light green granular chlorine if that makes sense. Hopefully, it will decay and come off slowly. Any thoughts as to what this is and how I can remove it?

Greg