algae control question

[alisonquilts]

Hi y'all,
I am a newish pool owner (this is our third summer), and I am trying to become less dependent on my local pool store. Don't get me wrong - the guys there are great, very helpful, and I have NEVER felt like they are trying to push unnecessary chemicals at me...but they are a forty minute drive away, and I feel like I'll never really understand my pool if I always get them to tell me what to add, and when!

So I have ordered the test kit recommended on the PoolSolutions site (Taylor K-2006), and it should arrive any day now. Once I have my lovely accurate readings how do I know how much of everything to add? Are there charts somewhere that list it all? Where is this magical place, and how do I get there?

My biggest issue is the outbreaks of what may be mustard algae we get every summer, but earlier in the year than most people get them in this area. I have been told this type of algae is much harder to beat with just chlorine (certainly the first year we had it shocking it didn't do a thing), and have used No-Mor Algae algicide successfully...but the PoolSolutions site says this shouldn't be necessary. This year's first (and hopefully only) outbreak happened despite the water chemistry reading as totally balanced...with test strips, and simple OTO test kit. I'm going around in circles here.

Other general info (that eventually should end up in my profile, I guess?): 25 000 gal custom vinyl freeform pool with SWCG system, half in shade and near pine and oak mixed forest (I'm guessing this is why we get the mustard algae).

Thanks for any info you can give me!
Alison

[Watermom]

Hi Alison, and welcome to the Pool Forum!
As soon as you get your kit, run a full set of numbers and post them. It is really impossible to help much without those numbers. For now, what readings do you get with the OTO kit? What source of chlorine have you been using? Any idea what your CYA reading was when you closed in the fall? It would be good to know that to compare it with your current reading.

What kind of filter do you have and what size of pump?

Hope the kit arrives soon. We'll be here and ready to help!

[alisonquilts]

Hi Alison, and welcome to the Pool Forum!
As soon as you get your kit, run a full set of numbers and post them. It is really impossible to help much without those numbers. For now, what readings do you get with the OTO kit? What source of chlorine have you been using? Any idea what your CYA reading was when you closed in the fall? It would be good to know that to compare it with your current reading.

What kind of filter do you have and what size of pump?

Hope the kit arrives soon. We'll be here and ready to help!

Thanks watermom. I'll post the numbers when I get the kit. But is there somewhere that lists "if your pH is x and your pool is y gallons, add z ozs of muriatic acid to change it to pH 7.6"? (just an example). I feel like I have seen this somewhere...other than the back of the package of whatever chemical I am holding! I guess what I am looking for is a collection of tables for each of the main chemicals we use.

Alison

[aylad]

Yes, there's one at thepoolcalculator.com, but I like the Beachcalc linked at this thread better: http://richardfalk.home.comcast.net/pool/BleachCalc262.exe

Janet

[Watermom]

That's the one I like better, too.

[PoolDoc]

Richard hosted it, but Michael Smith (mwsmith) wrote it.

[alisonquilts]

Thank you for the replies! I have a salt water system so the poolcalculator.com link is closer to what I was looking for...but I was actually hoping to find good old fashioned tables that I could print out, laminate and keep handy! (I am pretty old school about such things.) I can't figure out an appropriate search term to hunt for them. Perhaps I need to find a book about pool maintenance? (But so much would be wrong...)

Or maybe I need to spend an hour with poolcalculator and run a bunch of variables.

Any ideas?
Alison

[BigDave]

... But is there somewhere that lists "if your pH is x and your pool is y gallons, add z ozs of muriatic acid to change it to pH 7.6"? (just an example)...
It's interesting that you use pH as an example in that pH has got to be the least predictable value we measure in pool care. pH is affected by many interactions in the pool and trying to calculate the affect of a treatment is rough estimation at best.

Your K-2006 does have an answer to this: it includes Acid and Base Demand Tests. These let you measure the amount of treatment you'll need to adjust pH. It works like this: Measure pH, if it's low, add Base Demand counting drops until pH is where you want (Acid Demand works same way) - look up number of drops of treatment in the tables in the book that comes with K-2006 and find treatment dose.

The book has tables for other treatments as well - This may be what you're looking for.

Treat the doses you get from these tables as loose approximations only. They are helpful in determining how much of a chemical to buy and have on hand but less useful when it comes to actually treating your pool. At most, use half of any recommended dose, let it mix, measure, redose. This way (measure, dose, measure, dose, ...) you can avoid the inevitable see-saw of chasing numbers.

[aylad]

The other end of Big Dave's answer is...after testing your water on a daily basis for awhile, you'll learn the pattern of your pool...(ie. One jug of bleach adds "x" amount to MY pool, one pint of acid drops MY pH by "x" amount, etc.)

Everybody's pool is a little different.

[Watermom]

The book has tables for other treatments as well - This may be what you're looking for.

Don't use the book that comes with the Taylor kit. It is not helpful and will lead you astray. That was one reason Ben used to sell kits so that he could leave that book out of the kit as it causes lots of confusion.

[BigDave]

I should have pointed out in my post that (as Watermom and aylad suggest) you don't need those tables.
The best way to make your pool eaisiest for you is to learn what it needs and how it reacts - daily testing and treatment will give you the practice you need to get a "feel" for your pool.

[alisonquilts]

OK. I think I have some idea now: When I get my (longed-for and much anticipated) kit I will be able to get accurate measurements. When I have accurate measurements I can use poolcalculator.com to figure out my response (under-dosing, then testing, then re-dosing if necessary). When I have done this enough I will develop a sense (similar to using the Force) whereby I will see a result and have an intuition about what to do in response. I will then teach it all to my husband...

About the tables I am so hung up on - I think I will just copy the relevant bits off the backs of the various chemical packages into one document so I'll have a basic guide, since there doesn't seem to be the professionally compiled lists I expected.

Thanks for your help. If nothing else you have reassured me that it is not at all unnatural to be confused at this point!

Alison

[johnfluharty]

I bought some AuquaCheck Select test strips at my local pool store that came with a little booklet called "The Complete Guide to Pool and Spa Care" that has some charts in it which I use. With it I can keep my pool in pretty good shape. I have a more in-depth chemical kit that I use rather than relying on the test strips, but I still reference the charts to see how much of what to add.

[alisonquilts]

OK, so that sounds like what I was imagining. I will check that out.
Thanks!
Alison

[Watermom]

Just be aware that much of the available literature/pool care books out there are full of misinformation ...........

Taking care of a pool is not an exact science. You cannot know precise measurements of things to put in a pool that will take you to a precise reading. It just isn't possible.

Relax a little. I think you are making this harder than it is by worrying so much about the precision of everything. We don't want you to drive yourself crazy! :)

[johnfluharty]

The fact that they expect you to match colors visually is a good indicator that this is not an exact science. For me personally its not really about precision of what I add as it is remembering what chemical to add. I know, its only a handful of different chemicals, but then I need a grocery list if I want to remember more than 2 items. :) I do need to know whether to add 8 oz of something or 4 lbs, but I am too lazy to measure what I add precisely anyway, so all I need is a general idea, which the chart helps with, and I don't have to run inside to the computer. I guess I just haven't done this stuff often enough or long enough to really remember.

[CarlD]

Hi Alison!
The "How Much?" question is one we all deal with. The answer is usually you sort of feel your way to what does what.

HOWEVER:

With your pool, a 25,000 gallon pool, you CAN make a pretty good guess of how much chlorine a gallon of bleach will add. How much you'll need, is based on our "Best Guess" table that shows the level of Free Chlorine you'll need to maintain or to shock your water.

If you have 25,000 gallons of water, 1 gallon of ultra bleach (6% solution) will add 2.4 ppm of Free Chlorine. A gallon of 12.5% liquid Chlorine will add 5ppm of FC. A gallon of regular 5.25% bleach will add 2.1 ppm of FC.

So...say your CYA (stabilizer) measure is 40ppm, and your FC is 1 (assume your CC--Combined Chloramines-- is 0) The Best Guess table tells us your maintenance level is 3-6 ppm of FC and your shock level is 15 ppm. So you would need AT LEAST an addition of 2ppm of chlorine to get to maintenance level. 1 gallon of regular bleach would barely do it. 1 gallon of ultra would be better. But one gallon of 12.5 would take you near the top of your range, which I would suggest because you fell below 3 in the 3-6 range.

Now say your FC is 1 and your CC is 1 for a TC of 2. You would want to shock your pool up to 15ppm. You'd add 5 1/2 gallons of ultra bleach to get there.

I have NO idea how much powdered chlorine to use. I THINK 1# of Di-Chlor powder is about the equal of a gallon of bleach--but don't hold me to that.

How to add borax: If your pool is bordering on going under a pH of 6.9, you'll want to add a full box of Borax, into the skimmer. After an hour, if pH isn't in to at least 7.0 it, you'd add another box, and keep doing that until it reaches 7.0. Then I'd add a half-box every hour until I'm solidly in the 7.2-7.8 range (anything from 7.3-7.6 makes me happy). If my pool is below 7.4, but 7.2 or higher, I prefer to use aeration to raise pH rather than adding Borax.

There are acid demand and base demand tests and charts for adding stuff. I recommend that you NEVER add more than half of what the charts recommend of ANYTHING (other than chlorine). It's too easy to over-shoot your target, hard to fix, but easy to add more.

You'll never need to add calcium to your pool.

I hope this helps a little

Carl

[alisonquilts]

The fact that they expect you to match colors visually is a good indicator that this is not an exact science. For me personally its not really about precision of what I add as it is remembering what chemical to add. I know, its only a handful of different chemicals, but then I need a grocery list if I want to remember more than 2 items. :) I do need to know whether to add 8 oz of something or 4 lbs, but I am too lazy to measure what I add precisely anyway, so all I need is a general idea, which the chart helps with, and I don't have to run inside to the computer. I guess I just haven't done this stuff often enough or long enough to really remember.

Yes!! You nailed it! That is exactly how I feel! (And the bit about needing a grocery list for more than two items - too true.)

My angst over all of this isn't because I need everything to be precise, but that the three ways I currently have of getting test results generally give me three conflicting sets of values! When I do (finally) get the good test kit (it is taking a very long time to get here), I will now have confidence that the numbers it is giving me will at least reflect reality a bit, and I will go from there. At the moment I have the pool store telling me Cl- is 0, my test strip saying it is 0.5 and my OTO saying it is 2! Because I have a salt water system I am confident that there is at least some chlorine constantly being added, so I don't feel the need to fling buckets of chlorine around, but I don't want to mess with all of the other parameters until I get the Good Test Kit (my holy grail). And the water currently is beautifully clear...

Alison

[Watermom]

Trust the OTO reading over the other two.

(You're gonna love the new kit!)