Out of Town Again

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rocky

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Jun 30, 2009
62
Looks like the pool will be unattended next week for 7 or 8 days. I have finally gotten rid of the previous algae problem and don't want a repeat. Problem is how do I keep from getting algae? I have no tablets/pucks to put in the chlorinator and have no di-chlor. I do happen to have several bags of MPS. The CYA is 40 so I prefer not to add anything that will raise it. When I test the water, all parameters are in acceptable range and the water is clear.

Above when I mentioned the pool being "unattended" that applied to humans. I have no idea what kind of wildlife drinks, etc. from the pool at night. But they do. I don't want to dump a lot of bleach in there cause the grandkids might use the pool. I need some helpful ideas.
 
Here's what I did while I was away. I knew from past experience that I used about a quart and a half a day so I had the daughter go by and pour 2 quarts a day in the pool every evening. That way it would hold till I got back to test it and they could still swim when they wanted to.

If you've been keeping up with what you're using per day, and the kid(s) can go by once in a while, run the pump and dump some in there, you'll be golden.
 
If you cannot have somwone add bleach daily (or even every other day):

1) Shock the pool with bleach or liquid chlorine and cover it with your solar cover the night before you leave
2) if the grands are coming over, have them (or their parents) add some bleach to the pool (how much you typically add daily) when they leave and re-cover it

It is perfectly safe to swim up to shock levels for your CYA.
 
1. Covering with a solar blanket is not an option.
2. Having the parents of the "grands" add a to be determined amount of bleach is not feasible.

Since no comments were made regarding me using potassium monopersulfate (mps), my question is "will mps prevent algae from getting started"? I know mps is an oxidizer and not a sanitizer.

Looks like my other 2 options will be
1) raise the FC level high enough with bleach to prevent algae and make the pool "off limits" while the FC level is extremely high. I don't want to go this route though.

2) use a combination of bleach and mps. Based on my daily need of 44 oz of bleach I could figure the needed quantity of bleach to get me to the shocking level. My pH is 7.6 and the TA is at the lower limit of 90. MPS will lower these but I could bring them back up when I return.

Your comments??
 
You should not use MPS. It is more suited for indoor pools and spas and really won't help prevent anything here.

If covering is not an option, then your best bet is to use the chlorinator. Can you pick up some pucks? If you decide to use pucks increase the TA to 100-120 and PH to 7.8 before you leave. Make any adjustments when you return.

Without a way to protect your pool from uv rays (covering), you will lose 50% of the FC the first sunny day, so even if you shock it won't be a shock level for long if you don't cover it. MPS won't help you here.
 
MPS won't help at all.

It is essentially impossible to raise the FC level high enough so that you will still have a plausible FC level a week later in an uncovered outdoor pool unless your CYA level is extremely high (which causes other problems). You will lose about 50% of your FC each day to sunlight. After 8 days you will have less than 1% as much FC as you started with. To end up with FC at 5 you would need to start with FC at 640 (approximately), which is high enough to cause damage.

A trichlor floater is probably your best bet.
 
I'm dense but I do understand not to use the MPS.

I will increase the TA to 100 - 140 and the pH to 7.8 before I leave. I will buy some tablets and plan to put them in the automatic chlorinator. Should I plan on filling the chlorinator tank? It will hold about 15 of the tabs. How about the run time for the filter. Do I run it 24/7 or less?
 
Hey, Rocky,

When I test the water, all parameters are in acceptable range and the water is clear.
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That makes it sounds like you are testing with strips but I know you have the TF-100. Posting good test results always gets you better advice. It usually sends up a red flag to responders when folks report their tests as "normal", "acceptable", "ideal", etc.

Anyway, forget the MPS. I cannot tell you why but there's smart people on this forum that are telling you not to use it.....trust them.

1. The night before you leave, run your FC up to around 30 or so with bleach.

2. Set your chlorinator so that it is allowing a moderate to small amount of flow and stack it full of pucks.

3. Run your pump 12 hours each day.

4. On your return, shut off the chlorinator and do a complete set of tests to see where you are.

5. I doubt your CYA will go up more than 5ppm......10 at the most.

6. It is likely your pool will still be crystal clear.
 
I won't stray from using the TF-100 test kit. I am a believer and user of it. Let me see if I am using the pool calculator correctly. My current CYA is 40, if my FC is 6 then you want me to raise it to 30. That means 1045 oz of bleach. Is that correct? Wonder what crazy comment the checkout lady at Sam's Club will make when I purchase the bleach? Who cares anyway.
 

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My current CYA is 40, if my FC is 6 then you want me to raise it to 30. That means 1045 oz of bleach. Is that correct?
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Yes.

That 30 FC will keep your pool safe for probably four days as it slowly comes down.....the pucks will take care of the rest.

You could attempt it without any bleach at all but if you don't get the chlorinator set right, you may get an algae bloom or a big dose of CYA in the pool.

Naturally, you will still get the big dose of CYA if you have the chlorinator set too high anyway but the bleach will keep your FC up if it's set too low. So if your not sure of the chlorinator's output, set it low.
 
rocky said:
I will buy some tablets and plan to put them in the automatic chlorinator. Should I plan on filling the chlorinator tank? It will hold about 15 of the tabs. How about the run time for the filter. Do I run it 24/7 or less?
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In my pool I bring the FC up with bleach and then use 3 tabs in a floater when I'm gone for a week, and the tabs aren't completely dissolved when I get back. I count on about 1ppm FC per day from the tabs, which with my cover is about right. Your pool is bigger so I'd guess 4, then with no cover I'd double that to 8, assuming the chlorinator uses them up at about the same rate (I have no data on that). Eight 8-oz tabs in 21k gallons is worth about FC+21 (and CYA+13).

Pump on 24/7 is best when you tabs in the chlorinator, otherwise when the pump is off the pH will drop inside the chlorinator when the pump is off (the tabs will keep dissolving) and eventually damage it.
--paulr
 
Water is sparkling crystal clear. Tested the water this morning in preparation for leaving the pool unattended for a week. Here is where I am right now:

FC 15.5 : I will not add bleach till tomorrow night. Tody's UV will lower this measurement.
TA 80
pH 7.8
CYA - Did not measure. It was 40 on last test.

When I bring my TA in the desired range of 100 - 120, the pH, which is already at maximum, is going to go even higher. Should I plan to lower the pH with muriatic acid once I get the TA to the desired range? I know when I add the tri-chlor tablets tomorrow night the pH will start to drop.
 
When I bring my TA in the desired range of 100 - 120, the pH, which is already at maximum, is going to go even higher
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Bring your TA up with baking soda and you will have little affect on pH.

The small amount of pucks you use will not have too much affect on pH, either. I doubt they will move it .2, if that.

If it were my pool, I'd bring the TA to 100 with baking soda then test pH in a few hours and add enough muriatic to lower pH to 7.5.
 
Thanks to everyone for the great information you provided earlier this month. Returned home today and the water in the pool was sparkling crystal clear. The 3 inch tabs worked as expected. Here are my 7 PM readings:
FC 4
CC 0
TA 90
CYA 40 - not seeing that darned dot is like black magic. I guess the CYA could be slightly less but it is still in an acceptable range.
pH 7.6

Since my filter is off at this time I will wait till tomorrow morning when it is on and then add the necessary bleach.

Thanks again.
 
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