Help, even bleach disappears

[bcrumb]

My chlorine held at the 25 mark overnight. I got in the pool, reluctantly, with a small brush and went around all the fixtures(lights, returns, skimmers, rope hooks, and steps). All of them had algae, both green and black. In some cases long strips of black or dark green stuff were brushed away. I have seen this before, but I thought it would be good to clean it off while the water is at shock levels. I also snapped the covers off the tracks around the steps and cleaned them with the brush. I added one more gallon of bleach for good measure. I am going to do some research on this forum about the black algae. I have not addressed the cya issue yet, but it is raining now and hopefully that will dilute it some. My concern is whether I have a high enough shock level and how long should I maintain it at that level. I would like to be ready for swimming by Saturday.

[CarlD]

Actually, the chlorine won't hurt you at that level, but you will want to wear old suits that you don't mind being faded. And you probably don't want it in your eyes so goggles are a good idea.
If the level holds at 25 overnight for a couple of nights, I'd say you're good to go. But with the CYA at 100, you'll need to keep the level between 8 and 15 even while swimming. If it goes down to the 60-90 range, chlorine should be kept between 5 and 10.

Algae is VERY resistant to chlorine when it's attached or embedded in the walls and crevices of the pool. Brushing it out was a VERY good thing! And you should plan to do it regularly, like weekly, to control it.

Hope this helps.

[bcrumb]

Took a sample to Leslie's this afternoon. CYA read 90. This was after I drained about six inches of water yesterday and refilled. My chlorine was down to the 16 to twenty range also. This was with my test using the dilution method. Actually I ran it with a 1 to 5 ratio and it appeared to read about 4. Not very accurate but that is as close as I can get. I guess I am going to let the chlorine slowly decrease now and see where I stand. My concern is that the SWCG will not be able to keep the chlorine in the 5 to 10 range as you recommended. If that is the case, I guess I will continue to supplement, with cal hypo this time, until I can drain more water and refill to get the cya down further. Thanks, Carl, for all your help. I should have known better. I sort of blame Leslies for the incident because their guy acted like I was crazy to use bleach several days ago. He said since it was only 8.25 percent bleach that it was 91.75 percent something else and that was bad for the pool. That caused me to decide I would use some shock with the bleach. Also the heaviness and difficulties transporting the bleach added to this flawed response. As much as I have read on this forum, I really should have known better. Thanks again!

[CarlD]

Oh, wow!

Here's how I can help:
1) When your water is clear, you generally aim an SWCG to run at 5% of the CYA level--because it's a constant flow of Chlorine without ups and downs. Since most SWCGs request you keep your CYA in the 60 to 80 range, you'd keep your FC (that's Free Chlorine) in the 3-4 range. With your CYA at 90, that means you should keep it at least at 4.5--you've cleared up all the rest of the problems so you are going into maintenance mode--normal, daily care.

2) When you do NOT have an SWCG, the "Best Guess Table" is our/your guide, ie, the range I gave you. And, if you have an algae bloom, you do NOT want to use "Boost" mode from the SWCG as you will shorten your cell's life drastically. Best to use bleach or liquid chlorine. Safer, cheaper, extends the life of your cell.

3) You can find the "Best Guess" table at our sister site, PoolSolutions.com. You don't need to join, but I suggest you read EVERYTHING you can find there. It's an education in itself.

4) The Leslies guy is full of it. Bleach is made from brine so the OTHER 91.75% of it (assuming you are using regular bleach) is...SALT WATER! Yeah, that's right. And if you use nothing but bleach for 10 years in your pool you STILL won't have enough salt to run an SWCG. People without SWCGs add 50# bags of salt frequently because it makes the water feel softer. There's not nearly as much salt in bleach or liquid chlorine. Did he also try to "Pool Store" you and sell you "Phosphate removal" and calcium? If you know what you are doing, IMHO, they have some of the best supplies of any chain. If you don't, the salesmen/women may WELL try to sell you garbage--I've heard the "other stuff" argument from their people before. Buyer Beware!

5) Liquid Chlorine (LC), sometime sold in gallon jugs as "Liquid Shock" is nothing more than strong bleach, nominally 12.5%. I buy it in 5 gallon carboys, for $20/gallon. My deposit of $6 on each carboy(I have 3) was so many years ago it doesn't matter. I have a couple of screw on spigots, which are like an old-fashioned beer barrel tap, and I refill old bleach bottles and reuse and reuse them. Since bleach is has gone from 6% to 8.25%, the calculation is: If a gallon of LC is less than 50% higher than a gallon of 8.25%, the LC is cheaper to use. Otherwise, the bleach is cheaper. When 6% was the "Ultra Bleach", the ratio was double--LC could be up to 2x the cost of bleach to be cheaper.

6) If you use Cal-Hypo, track your Calcium Hardness. When it gets to 400ppm, you should stop using the Cal-hypo. When it hits 500ppm, I would say you MUST stop using it or risk your water going milky and getting scale on metal parts. Personally, I rarely use the stuff and only use Tri-Chlor in the spring or when I refilled so I could boost my CYA at the same time as my chlorine. But I also watch pH as Tri-Chlor is VERY acidic.

7) While you can ALWAYS use bleach or LC, Cal-Hypo, Tri-chlor and Di-chlor all add stuff you have to watch. Used correctly, they are beneficial. Used incorrectly, they can cause problems. Test, test, test!