New Pool Owner bought a test kit

Hi there...long post, but somewhat introducing and making sure I'm on the right path....

We just bought a house in July with an awesome in ground pool - we weren't looking for a pool but when we found this house it was an added plus as we both love the water. It's 20x40 with roman ends and is probably around 40,000 gallons - vinyl liner with 2 skimmers, drain in the deep end... I had tested with strips that the last owner left as well as a chlorine/ph test and everything seemed pretty good - but it was very difficult to match the colors in the tests. Went to the pool store once and they tested and tried to sell me lots and lots of stuff but I just bought some shock and some tablets for the chlorinater as I wanted to make sure it was sanitized at the very least...and the guy just seemed to be 'selling' me on chemicals.

Had one sign of algae - some green on the light housing and ladder - bought some algaecide from the pool store (didn't know what I was doing and based on what I'm reading here...who knows if that or the shocking did it)... all-in-all since July we've had a beautifully clear pool with no irritation to swimmers eyes/nose...

I thankfully found this site and got to Walmart and got a 6-way test kit as here in the Chicago area we're about done for the year and wanted to make sure I was set. Funny side note.... at my local Walmart they had cholorx bleach in the pool isle. (I fully intend on getting a Taylor kit in the spring)

So tonight I tested and here are the results. As far as I can tell things seem ok - chlorine is a bit low for the CYA based on the CYA chart....Oh, and some seemed to be between colors....

PH between 7.5 and 7.8
Chlorine - between 3 and 5
hardness - 550 (does a number this high still not matter for vinyl?)
Alk -120-130
CYA - 90

Water temp is around 78 with the heater - oh and we're on a well here so any adding that doesn't come from the sky comes from the well....

I've been using the trichlor tabs in the chlorinater and I thought I read somewhere they're the culprit for a rising/high CYA level - is this true? I couldn't find where I read it even when searching....

I fully intend on BBB'n my pool to close it and maintain it next year and I think I'm going to have the pool store close/winterize so I don't mess it up and with our 2 month old and work schedule I'd rather just have it done this year.

Any thoughts, questions or suggestions for my water?

Hi, Doug, and welcome to the forum!! We're glad to see you here.

Sounds like you've been doing your homework--congrats! You'll find it so much easier and cheaper when you have control over your own pool and are not at the mercy of the pool stores, as you've already found out.

Just have a couple of comments....First off, your CYA level is high, which is from use of the trichlor pucks. I would now discontinue the pucks and switch to another means of chlorination. Because your CH is also high, I wouldn't use any more cal-hypo (probably the ingredient in the powdered shock you've been using) so your best bet is to switch to bleach. With a CYA of 90, that means you need to keep your chlorine level at 5-10 ppm at all times, so your chlorine is a tad low. Since you're already at the upper end of the CYA range, I would try to keep the chlorine level at the upper end of that range, as well.

Your CH, if it were low, wouldn't be an issue in the vinyl pool. However, with it being high, if you continue to use cal-hypo you are going to end up with milky water that will not filter out. So...if the water is clear now, that's great--but I wouldn't use any more calcium for chlorination.

Your alk is a little high, but ok for vinyl, as well as your pH. You could leave them alone, or wait until after you decide what to do about the CYA and CH to adjust them. Also, if you'll be closing the pool for winter, it's probably best to wait until you open in the spring to adjust them anyway. I strongly recommend that you drain/refil about 1/2 of your water, if that's feasible for you, in order to lower your CH and CYA levels to something a little more manageable. In very hot, humid, sunny climates like mine, high CYA is a good thing and helps cut my chorine useage, but in most other pools, it's better to keep it a little lower (30-40) in order to be able to maintain lower chlorine levels. It's up to you, but it's a suggestion. Also, if you're going to close the pool for the winter and don't do it properly, algae that blooms over the winter can allow bacteria to break down the CYA into byproducts, including ammonia, that create a huge chlorine demand upon opening until it's all broken down. (Just another reason to consider lowering the CYA before winter closing). But again, it's your call.

Since you're using well water, have you had it tested for metals? Well water often has iron in it, which can create a whole other group of problems, so if you haven't had it tested yet, I advise you to do so before you decide whether to drain/replace water or not.

Otherwise, it looks like you're on the right track--congratulations on the new home and pool!! :cool:

Janet

Janet has pretty much covered the bases with you and given you the same advise the rest of us would have given. So, just wanted to say hello and welcome to the forum!

Would it be a bad call if I did close it improperly on purpose to let the CYA break down? Would the chlorine demand just be to clean up the algae bloom or are there other risks to consider? If this will lower the CYA how would one close improperly - just put the cover on without adding bleach?

Regarding the metals the last owner did a bunch to clear that up, but I haven't looked at that and I don't have the results around from my test but the last time the previous owner had it tested Copper, Iron, Manganese were all listed as "0" or "no" - since then I've added probably 4-5 inches back to the pool as well as drained some with some of the heavy rains we had here in July/August. Seeing as the house has an iron filter I'm guessing I added some iron to my pool.....

In looking at the tests from the previous owner....it's Interesting that CYA went from 35 to 65 to 88 from May 14th to June 14th (tested every 2 weeks)...also a note on this paper about phosphates being high....

Don't worry about the phosphates--that's a new, improved way for the pool store to separate you from your money. Ignore them. The CYA went up like that because of the use of trichlor pucks--they'll raise CYA in a hurry if you don't keep an eye on it, which is why they tend to get people into trouble.

If you have an iron filter before the pool, odds are you're removing most of it before it gets into the pool. However, once it gets into the pool, you can either add metal sequestrant, which keeps it into solution (but does not ever remove it from the pool), or you can run the water past a high chlorine source and intentionally precipitate the iron (copper, manganese, whatever) out onto a filter. Your call--I don't have much experience with metals but there are folks in the metals forum (specifically pooldoc and mbar) that do.

As far as letting the algae break down the CYA--I don't recomend that route, but again, it's your pool. The problem with that method is that the bacteria break the CYA down into ammonia and other byproducts. So when you open the pool, you're going to have to maintain your shock level for a long time to both clear up the algae bloom AND break down all the ammonia, and it can take LOTS and LOTS of chlorine to do so. I think you'd be better off just to chlorinate with bleach throughout the winter and just drain off as much water as you can as it rains or snows in your area, allowing the rain/snow to do your refill for you. The CYA will come down that way, and by the spring should be very manageable. You just may have to consider a different method of chlorination than trichlor for next summer! :)


Janet