New to the forum - Trying to get a handle on pool chemistry

Howdy,

I have a 15'x48" Intex AG pool that the kids love. We set it up and used it for about 3 weeks when we got an algae bloom. I needed to take it down and get the ground level so we drained it and started over. Pool was great again for about a week and a half. Now its starting to turn green again.

I spent a few hours reading through a bunch of the posts and need to get a better test kit. The one I have uses drops but does not have anything to test CYA.

This evening I added a half a bag of HTH shock and swim and also muriatic acid to bring the ph down. It was really high (maxed out on the color chart). Tomorrow we plan on getting some bottles of bleach and using that to manage the chlorine.

I'll post the water test results when I get them tomorrow.

Hi, and welcome!

Did you add any stabilizer when you refilled the pool? If not, then the sun is consuming your chlorine very quickly and would explain why it turns green so quickly.

Post your water test results, along with the ingredients of anything you've added to the pool, and we'll be glad to get you going in the right direction!

Meanwhile, add 1/2 gallon of plain 6% household bleach each evening, after you finish swimming or near sunset (which ever is later), till the algae is gone.

Ben

Just noticed I am able to post...

When I filled the pool a few weeks ago, I did use a half a gallon of liquid stabilizer that I had left over from when I filled it the first time. I had been using stabilized tablets in a floater until they were used up last weekend.

Had the water tested yesterday at the pool store while the good test kit is on the way
FC: 4.0
TC: 4.0
CYA: 50
TA: 90
pH: 7.6

I started to kill the algae with a big bottle (180 oz) of 6% bleach yesterday evening. I tried to test the water this morning and the cheap kit said it was at least 5ppm so I added another bottle. I didn't get home until it was dark so I couldn't tell if the green is turning to grey, but I still cant see the bottom. I did add another bottle this evening so I imagine the chlorine levels should be high enough to kill the algae. I'll post an update tomorrow after I can see the color of the water.

Morning Update...

Water is clearing up. I could see the bottom this morning. The color is turning from green to greyish white. There is a bunch of what looks like dirt on the bottom now. I'll set up the vacuum I have rigged up to try and clean that up tonight.

My cheap test kit had the color very deep orange which is different than when I tested the last couple of times so I think the algae is dying off and more chlorine is staying in the water.

The fact that the water is clearing and you're seeing evidence of dead algae is great...keep that chlorine level up, keep your filter running, and make sure to keep an eye on your filter pressure and clean it as needed. The chlorine will kill the algae, but it is the filter that will remove it from the water (other than what you're able to vacuum up)

You can force your cheaper test kit to measure higher chlorine levels with this method: http://www.poolsolutions.com/gd/how-...d-testkit.html

It's a ballpark, because you lose a little accurace with each dilution, but it'll be better than just guessing. You want to keep the chlorine level up at 15 ppm until the pool clears, and until you're not losing more than 1 ppm of chlorine when testing in the evening after sundown and again in the morning before the sun hits the pool. Once you're at that point, you can let the chlorine level drift back down, but with a CYA of 50, you never want to let it get below 3 ppm, EVER. And since your CYA is at the top of the range, I would keep it closer to 5 or 6 ppm if you can, just to give yourself a little wiggle room. (See the best guess chart at http://www.poolsolutions.com/gd/best...e-chart.html#a for a better explanation of that)

Janet

One question...

How fast does the CYA level drop? The new kit will not arrive until next week so I don't have a way to test if the CYA is dropping. I will continue to monitor the chlorine best I can and try to keep it at 15ppm until the pool is clear.

Jamie

CYA levels are pretty consistent throughout the season once you add it. You lose a little to splashout and refill but over all, not much.

I ran the vacuum to waste last night. I could see a big color difference from where I vacuumed to where it still had junk and could see the color in the clear pump lines change to brown when I was sucking up the junk so it was really bad. I needed to refill about 5" of water after that was done so I also added one bottle of bleach to make sure chlorine levels were plenty high. This morning the water is a nice blue color, but still cloudy. I took a sample in to check CYA levels again and they said its now at 10 probably due to the changing out of so much water. I have some stabilized tables left over. Can I use them to bring the CYA level up some and supplement the bleach for chlorine or will that throw things off. I don't want to undo whats been done so far. Thanks so much for all the help so far.

Jamie

You can absolutely use the tablets to help raise the CYA levels--just keep an eye on your pH and make sure it doesn't get too low--trichlor tabs are acidic and can drive pH downward. It's fine to use the tabs and the bleach at the same time in the pool--after all, it's all chlorine when it gets in the water. Just don't let the bleach and tabs come into direct contact with each other before they're in the pool.

Janet

Please ignore the question in the last post. After further investigation, the tablets I have left over are not stabilized. They only contain calcium hypochlorite.

I am guessing that CYA of 10 is really too low and should be increased. Since the good test kit is not supposed to arrive until late next week, and don't want to over do it, should I wait until next week to try and mess with it and just try and keep the chlorine levels above 5 until then?

Go ahead and add a lb. of stabilizer. A week from now, test your level and see where you are then. It should be somewhere around 35ppm or so if the reading of 10 is correct. (It really isn't possible to differentiate levels that low but you know that is is low, so adding a lb. should be about right.) I estimated your volume to be around 5000 gallons.

Had the water tested at the pool store again today to see how the CYA is doing.

FC: 5
TC: 5
CYA: 50
PH: 7.4
TA: 220

The pool is nearly clear, just a little bit of cloudy, but this is the best I have seen it since it was filled.

The pool store person mentioned that the TA level has high and would rust out the metal frame. When I add bleach, the PH rises so I use acid to bring it back down, will this normal use bring the TA into check over time? Or do I need to get this down sooner and start adding acid at regular intervals and then use something to bring the PH back up?

Thanks again for all the help so far... The kids finally will get to use the pool again this afternoon and are extremely happy.

Jamie

Sounds like you're making some progress--just keep the pump running and clean the filter as your pressure indicates until all the dead algae is out of the water. And make sure that your chlorine level never drops below 3 ppm so you don't have to fight that battle again! :) Your TA level is not high enough to cause concern about rusting. Also, it is normal to have a temporary rise in pH when using bleach, since the pH of bleach is 13! However, as the bleach is "used up", the pH goes back down--so don't adjust your pH just to keep up with the bleach.

You don't list a reading for calcium hardness--if your CH level is high, then dropping the TA can have a clearing effect on the water. Also, if you were to lower your TA down to around 80 or so, you might find that your pH is a lot more stable. However, if the TA of your fill water is 220 or higher, then it'll be a constant fight to keep the TA down due to frequent refilling, and since it's not really causing you problems, it really can be left alone for now. Those things would be the determining factor in whether or not I would lower the TA if it were my pool. If you decide to do so, here is the procedure: http://www.poolforum.com/pf2/showthread.php?t=191

Above all: if the kids are going swimming in a cloudy pool, make sure you keep a good eye on the swimmers, especially in the deep end--cloudy water can make it hard to see somebody who is in trouble!!

Janet

Thanks Janet,

I must have forgot the CH. It was 120. Thanks for for the info. I'll not worry about the TA if the PH seems to be stable until at least later in the week when the good test kit arrives.

I'm not too worried about the water being slightly cloudy. The pool is only a 15' x 48" AG pool and I can see the bottom, but thanks for the advice.

Thanks to all again... I think I'm finally getting a hold of the method to the madness.

Got the kit today...

FC: 4.5
CC: 0
ph: 7.6
TA: 220
CYA: 50

I didn't test the CH. I'll check it again tomorrow morning to see if FC drops any and add some bleach if it does. I have a single non-stabilized puck in the floater right now. The pool never has cleared up to perfect. I can see the bottom, but have to strain to see any leaves that need to be cleaned out. The kids are having a blast though so no problems there.

Jamie

Now that's what we like to hear! :cool:

Janet