Backwashing and shocking

[Watermom]

Hi Judi,
Not Janet here, but hope I'll do!

With a cya of 70, your chlorine levels are not near high enough to keep algae from forming much less to fight it!

Stabilizer . . . . . . Min. FC . . . . Max FC . . . 'Shock' FC
=> 0 ppm . . . . . . . 1 ppm . . . . . 3 ppm . . . . 10 ppm
=> 10 - 20 ppm . . . . 2 ppm . . . . . 5 ppm . . . . 12 ppm
=> 30 - 50 ppm . . . . 3 ppm . . . . . 6 ppm . . . . 15 ppm
=> 60 - 90 ppm . . . . 5 ppm . . . . . 10 ppm . . .. 20 ppm
=> 100 - 200 ppm . . . 8 ppm . . . . . 15 ppm . . .. 25 ppm

As you can see in the chart above, you need to keep your cl between 5-10 ALL the time and when you need to shock, you'll need to take it up to 20ppm. Since you are reporting a CC reading of 1, and you have low FC level and you are seeing algae, all these things tell you that you need to shock the pool and try and hold the cl at 20. The more times per day that you can test and add bleach to get your cl back up to 20 the better. The very minimum is twice per day: early morning and in the evening when the sun is off the pool. But, if you can test 3 or 4 times per day it will clear up faster. The key is to sustain the high cl reading and not let the FC yo-yo up and down. When you get to the point where you are not losing more than 1ppm of cl from sundown to sunup and when you have a CC reading of 0 and no more algae, then you can let your cl drift back down to between 5-10. Never below 5 however or you will fight algae again. Also run your pump 24/7 while you are trying to clear this up. Also, brush the sides and bottom of your pool daily.

What exactly have you added to this pool -- meaning ingredients, not just "shock"? Your cya is already high at 70 so you really shouldn't use any trichlor pucks or dichlor powder in your pool. Best to stick with bleach or liquid chlorine.

What is the volume of your pool?

[jmcrae]

Thanks Watermom!
Our pool holds 8000 gals. We have always exclusively used a product called Shock PLUS (by aqua chem). They are 1 pound packets that treat 12,000 gals. I don't know why we started using an entire packet per treatment, but we did. Like I said before, our problems started three months ago with our new pool. The active ingredient is sodium dichloro-s-triazinetrione (58.2 %). The remaining 41.8% is "other ingredients". The package instructs to use once a week to create sparkling water, reduce chlorine odor and eye irritation, and does not increase pH.

I can work on the pool in the morning and evening, but for the rest of the day, this being Texas, the sun is unmerciful. Could it be the sun? We lost a shade tree and one of our pool umbrellas so we have many more hours of direct sun on the pool this year. In any event, I will start the bleach regime and let you know.
Judi

[Watermom]

In your pool, each quart of 6% bleach will raise your cl level by just about 2ppm. Also, with a cya level of 70, you shouldn't use any more dichlor (shock plus packets) as they are stabilized (which means they have cya in them) and you don't want your cya any higher.

Keep us posted!

[jmcrae]

You bet Watermom! Thanks ever so!

[jmcrae]

Watermom - I'm really, REALLY, new to this testing stuff, so please bear with me (after you finish laughing).

I started this morning at 7 am; I vacuumed then backwashed; I added 1 quart of bleach which resulted in the following levels: FC - 5; TC - 5; CC - 0; and pH 7.8.

At 2:30 I added another quart of bleach and got the same levels.

The little measuring container has two ports; one labeled Cl Br, and the other labeled pH.

The Cl - Br side looks like this:

Cl Br
5 10
3 6
2 4
1 2
.5 1

The pH side:

pH
8.2
7.8
7.5
7.2
6.8

My question is: How do I measure 10pmm and 20pmm if it's not marked on my container? The kit I got from Leslie Pools cost $47. Is there another kind of measuring container with higher levels on it? Am I making any sense?

Thanks for your patience...perhaps we should move my posts to kiddy/remedial?

Judi

[Watermom]

I hate that you already spent $47 on a kit, because you really need a better kit. We like the Taylor K-2006 and it will let you test higher cl readings than just 5ppm. Read more at this link:

http://www.poolforum.com/pf2/showthread.php?t=10006

In the meantime, you can make your kit go higher than 5 by using dilution. Take one part pool water and an equal part of distilled water, mix, and then run your test with this. When you get your result, multiply by 2. To go higher than that, take one part pool water and two parts distilled, multiply results by 3, etc. This dilution method is not super accurate but is better than what you can do now. You really should consider a better kit. It will pay for itself in no time by avoiding problems in your water.

How does the water look? You are not adding enough chlorine at a time to get to shock level. When you test, add enough bleach to take your cl level back to 20. Each quart adds 2ppm so if you test and it is 5, then you need to add 15ppm which would require 7 or 8 quarts of bleach added all at one time. If you don't take it to shock level, you will never clear the pool. Try and test at least two or three times a day and each time raise the cl back up to 20. If you do this consistently until you can go overnight without losing more than 1ppm of cl, then your pool should clear right up. After you can hold cl overnight, then let the cl drift back down to 5-10.

BTW -- Don't worry about asking what you think are silly questions. We were all once pool newbies. You'll get the hang of this and before long, you'll know exactly what to do.

[CarlD]

Just a caveat:

If your kit is the "DPD" kit, using the "DPD" test for chlorine, you cannot use the dilution method--that only works on the OTO chlorine test.

But the good news is if you can find an OTO kit that measures to 5ppm (and they are around although most are only good to 3ppm) you can use dilution with that--and they aren't expensive. You CAN use dilution with a 3ppm kit, but you have to dilute the pool water with 4 parts of distilled water to measure to 15ppm. With a 5ppm OTO kit you only need to dilute with 2 parts of distilled water to get to 15ppm--far more precise.