Trying to get a handle on pool chemistry

[Strop]

Good morning,

This is my first post asking questions. So I've done some reading on this forum regarding balancing chemicals, I've purchased a TF100 kit and a speedstir and now I'm about go it alone, that is cut the cord from the local pool supply store.

I have many questions about pool care, the equipment, etc. My main task right now is to get the chemistry balanced. I'd like to use up what supplies I have left from the $$$ pool supply store. But if that's not a option then I'll sell them or get them disposed of properly.

I'd did my first test yesterday. Everything seemed to go ok. A few little gotchas as far as handling the bottles. One of the bottles sprayed me when being opened for the first time. Didn't expect that but I'm still alive. Ironically it was one of the bottles with the most warnings on the label.

I did the daily test first...

Cl is greater than 5.
Ph = 8.0 or higher.

FC = 7
CC = 0.5
TC = 7.5
CYA = 100
TA = 140
CH = 975

I've been using Power Powder Plus (73% Calcium Hypochlorite) and 3" Jumbo Tabs (Trichloro-s-triazinetrione).

I took what was left of the 3" tabs out of the pool and added 48oz of Acid (according to the PoolMath App).

What should do next? I'm planning to do all the tests again today. I need the practice...

With Calcium Hardness being so high I really need to drain. My question is can I wait until the Fall or Winter?

Can I continue to use Power Powder Plus until it is used up then switch to bleach?

Thanks!



Strop

 

[mknauss]

Good job on the test kit and SpeedStir! Sorry about the spraying bottle ---

You show your CYA of 100. Do a diluted CYA test to see how high above 100. See Step 8 - Pool School - CYA

You need to stop using the Cal Hypo, now. Your CH is high, can be managed, but with diligence. You are in the scaling tendency range with your high CH, high TA, and high pH. You lowered pH, good. If you cannot drain any water (though your CYA may force that option) you need to lower your TA. See - Pool School - Lower Total Alkalinity

Great start.

 

[Strop]

Thank you MKnauss for the quick reply!

I'll do the tests and then repost.

Yeah, I've got a fair amount of scaling at the waterline.

Cheers!

Forgot to add to my signature. Inground pool with plaster/marcite.

 

[domct203]

Welcome to the forum.

As mentioned stop with the powdered & solid forms of chlorine. Cal-Hypo is what is driving up your CH, Trichlor is driving up the CYA. For every 10ppm of FC added by Trichlor you also gain 6ppm of CYA.

Switch to liquid chlorine, aka bleach. Regular laundry bleach is fine as long as it is unscented and not splashless. It comes in 6% and 8.25% strengths.

Pool bleach, sometimes called liquid shock, comes in 10% & 12.5% strengths.

 

[mknauss]

Yeah, I've got a fair amount of scaling at the waterline.

Once you decide to do a drain/refill to lower your CH (sometime in the near future) you might contact a company that uses soda blasting to clean off the calcium buildup. Costs some money, but it works. Then, with TFP and your own testing, you will not get that calcium build up again.

Take care.

 

[Strop]

Ok, retested a short time ago and here are the results.

Cl = 5+
pH = 7.5
FC = 5.5
CC = 0
CH = 850
TA = 120
CYA = 140

I used the method for measuring high CYA as described here - See Step 8 - Pool School - CYA.

 

[kabutotx]

Rule of thumb is your FC needs to be 10% your CYA to keep pool algae free. Use liquid chlorine to get it up and maintain it. Drain when you can and keep pH below 7.6 to prevent scaling with that CH.

 

[mknauss]

OK -- you have some decisions.

What does your water look like? Any visible algae or cloudy water?

With that high of CYA, you need to maintain a FC of 12, thus you need to add each day to FC of 15 or so.

You are on the edge of scaling. And as you stated before, you have scale on the waterline probably due to just a bit higher pH and you are in scaling tendency solidly.

I think you would be much better off changing out your water. But as I said previously, you should try to get the waterline cleaned up before you put new water in.

With this high of calcium and CYA there is a way to change out the majority of your water with out draining. It takes some effort, but we can explain it if that is what you want to.

Some other members will post their thoughts.

Take care.

 

[Strop]

Thanks for the quick replies...

I'll start looking at when/how I can drain and refill. We currently don't have water restrictions (I think) in effect in this area but I need to check and how this might impact requesting a refill from the Water District.

PoolMath is suggesting I add 267 oz of Chlorine. I just went to Target and purchased 4 x 121oz of the generic brand (up & up) bleach. The label says 8.25%. So, I'll add this amount and then retest again tomorrow.

I think I can get my hands on a Soda Blaster. So I'm contemplating doing the clean-up myself. I did some reading about acid washing recently. That seems pretty straightforward too. I need to post a few photos showing the condition of the plaster. The pool was re-plastered about 5-6 years ago. I'll confirm that. There are some issues with water draining from the Jacuzzi to the pool overnight (when the pump is off). Photos will help explain this. The interface between the plaster and the rock features in the jacuzzi is not optimal. There are some gaps. I suspect this is where the water is going.

Anyway I concentrate on getting the chemistry somewhat balanced first.

Thanks again for the assistance.

Cheers!

 

[Strop]

Hi,

My test results for today...

Cl = 5+
pH = 8.0
FC = 11.5
CC = 0.5
CH = 750
TA = 120
CYA = 100

The PoolMath app suggested adding 40 oz of acid which I just did.

So, it appears to be going in the right direction. I think my testing technique is improving too. Not sure how much that would effect the results but interpreting test result color would be my only concern.

MKnauss,

In answer to your questions. I've never really had any cloudiness. The water always looks clear (to me). But! In my the 3+ years of pool ownership I've always had some amount of algae. I brush the walls 2 to 3 times a week to help keep it under control. Before adding 267 oz of bleach yesterday there were a few spots of green on the walls. Its always the same places and varies in how concentrated it gets. I try to not let it get out of control. Today there doesn't appear to be any algae. I'm really chuffed about that! I feel like I've just begun to get the pool under control. Until TFP I've been a clueless idiot. Its almost comical if don't think about the countless dollars and time I've wasted at the local pool supply store. Hmmm, anyway moving right along.

Thanks again to you the people on the Forum and to the people who maintain the Forum and the PoolMath App.

Cheers!

 

[mknauss]

Check this thread for what a clear pool looks like -- TFP Clear in North Dallas - there is water in there

 

[Strop]

Yeah, I'll have to reset my thought of what a clear pool like like after reading that post.

I have some amount of cloudiness...

Cheers!