First appearance of Algae

I just started using the BBB method of pool maintenance about 8 weeks ago. The cell on my salt system quit working and I decided to give this a try. The pool has looked perfect from day one and it has been simple to maintain the chemical levels, but last evening I noticed some brown spots appearing on the liner. I read some of the posts on algae and I am a little confused about killing it with a high level of stabilizer in the pool. My level has been at about 95 ppm since early in the season since I added 10 lbs. of cyanuric acid instead of alkalinity increaser. If anyone has any suggestions I would welcome the help. I have a 24,000 gallon pool with a vinyl liner. My pump runs 24 hours a day and I have a Pentair DE filter.

Your site is great. I always suspected you did not have to use chemicals from a pool store and the poolforum was the first place that showed me how to avoid them.

Hi, and welcome to the forum!!

In order to kill algae with a high CYA, you just need to up the chlorine level based on the CYA (see the best guess chlorine chart linked in my sig for more info and the chart). Basically with 100 ppm CYA, this means you need to raise your chlorine to 25 ppm and keep it there by testing and adding more chlorine (we use bleach for this) as often as you can, until the pool clears and you can go from one night to the next morning before sunup without losing more than 1 ppm of chlorine.

If you'll tell us a little more about your pool, particularly your volume, and post a set of test results on your water taken with a drop-based kit, along with a list of what other chems you've been using, we'll be glad to help you figure doses or offer whatever help you need. :)

Janet

Would the shock amount add that much more CYA? Would that be about 12 oz for 3lbs of shock or less than 10 ppm. You are right 12% bleach is the better. From a transportation issue I thought the bulk was difficult and personally the 12% I could only buy in wholesale amounts. But to the OP liquid chlorine is the best.

Janet,

Here are the vitals on the Pool:

Volume: 24,000 gals
Liner: Vinyl
Pump:3/4 hp Centurion
Filter: Pentair FNS-48 (120 sq ft area)

I have been using 6% bleach, baking soda, borax, and muriatic acid to adjust ph. I have not needed much of anything besides the bleach (about 3 quarts per day) for about 6 weeks since my salt cell died. I do not have a test kit yet, but I use 2 pool stores that use the drop based method.

My levels from yesterday are:

FAC: 3 PPM
TAC: 3 PPM
CYA: 99 PPM
TA: 90 PPM
pH: 7.8

I have had no troubles with the pool all summer. We have not had any rain for over a month now and maintenance has been easy. I have about 8 lbs. of lithochlor shock (29% lithium hyperchlorite) I would like to use if possible but if that can cause problems I have plenty of bleach on hand.

I am also not sure if I actually have algae now either. There is a brown stain on the bottom right along the seam where the slope for the deep end starts. It is about 4 to 6 inches wide. It is not even visible when the sun is shining on it. You can only see it when the sun is setting and you cannot brush it off. I do not have much experience with algae. I have only seen it once in the 6 years we have owned the house.

I hope this answers your questions. Thanks for helping me.

Paul

You really need to get your own kit so you won't have to rely on the pool store. And, with high CYA, you're going to have to run high chlorine levels as Janet mentioned. You need a kit that can test as high as you're going to need and the K-2006 kit will do that. If you haven't already done so, please read the Best Guess Chlorine Chart in Janet's signature above. With a high CYA and chlorine at only 3ppm, you are going to have algae problems. (It is actually very likely that you really have CYA over 100 since that test can't differentiate values past that.)

To determine whether or not you have an algae issue, the easiest way is to test the chlorine at night after sundown and then again in the morning before the sun hits the pool and see if you've lost any chlorine in that time. If you've lost more than 1 ppm, then you have something eating up your chlorine and the pool needs to be shocked. If not, then you know that's not the issue. However, this requires being able to do your own testing. In your case, if you have any doubt at all, I would shock the pool anyway just because your chlorine levels are way too low for your CYA level.After that, you're going to need to keep your chlorine at a minimum of 8 ppm to make sure the algae stays away.

I don't see any problem with using the lithium chlorine that you have--I've never used it, but I know that it's one of the most expensive forms of chlorine that you can use--I certainly wouldn't go buy any more of it, but I don't think it would be a problem to use up what you already have. After that I would switch to bleach.

Janet

Quote:

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Originally Posted by ranand

Janet

Would the shock amount add that much more CYA? Would that be about 12 oz for 3lbs of shock or less than 10 ppm. .

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Ranand,

If this poster were using the dichlor to maintain a shock level of 20 ppm for a few days, as would be required to kill off an algae bloom, his/her CYA would skyrocket. Dichlor gives 9 ppm of CYA for every 10 ppm of chlorine delivered. Dichlor would be a bad idea for this poster's issue.

Dear Watermom,

I do know I need my own test kit and will get one immediately. I am not working currently and am trying to avoid any expense possible. I have read the Best Guess Chlorine Chart and am wondering if maintaining chlorine that high will be irritating to swimmers? Do you think I should dump about 8,000 gallons of water to get the CYA level down? That is what the pool store suggested.

Thanks,

Paul

Janet,

I will shock the pool with the Lithochlor and get a test kit. I have been using bleach up to now and had great results. I guess i need to get the level up to 25ppm and then maintain it at 8.

Thanks,

Paul

Sounds like a plan.

Maintaining your chlorine levels "that high" will not be irritating to swimmers. A pool with CYA of 100 and a chlorine of 8 ppm is no more irritating that a CYA of 30 with chlorine of 3. The CYA makes the chlorine less aggressive (hence the need to up the chlorine levels when the CYA levels go up). You can even swim at shock level if you want...it might irritate the eyes a little, and I certainly wouldn't wear new, or Lycra, suits, but it wouldn't hurt you. The elastic in the newer fashion suits doesn't hold up well to high chlorine, though, so wear an old suit.

As far as your CYA level goes, you can drain/refill part of the water if you want to, to lower the CYA levels--it would allow you to run lower chlorine levels. However, I run my pool at 90-100 CYA on purpose because I lose substantially less chlorine to the sun that way than I do at lower levels. It also allows me to dose the pool every 2 or 3 days, instead of everyday and still keep my chlorine where it needs to be. As long as you keep it in the ranges per the chart, for me, the higher CYA pool is easier to run. The only downside is if you have an algae bloom--it takes an immense amount of chlorine to clear up, but I find it easier to keep the algae blooms away with the slower-disappearing chlorine from the higher CYA levels.

Your choice. :)

Janet

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