Newbie. First pool chemistry results.

[Urodoc]

I decided to take over my pool care from the pool guy because the weekly service was getting worse (new employee), and I wanted to save some money.

They cleaned the pool for the last time on Wednesday. It looks fine (no algae). I have lots of trees, so I'm putting in a poolskim tomorrow.

It has been raining all day today, but I wanted to learn how to use my K-2006 so I tested anyways.
Here are the results:

FC 4.6ppm
CC 0
pH 7.4
TA 70
CH 280
CYA 180

They have been using trichlor pucks in my floater and my inline chlorinator. I had to dilute the pool water 50-50 with tap water to get the CYA level.

So it looks like I have to drain the pool. :? Any guess on how much I should drain? It's about 37k gallons.
Thanks for your help.

 

[Urodoc]

ugh, the pool calculator says 78%. Wow!

I'm guessing that I don't add any other chemicals until I refill the pool and retest.

 

[257WbyMag]

What type of pool do you have? According to your sig line, you have an inground pool but is it vinyl lined, fiberglass, or gunite? You want to be careful when draining to make sure that you don't float your liner or pool. If you have a high water table or anything, it's best to do a little at a time.

 

[Urodoc]

Gunite. I amended my signature.
I think my water table is pretty high. We resurfaced the pool in 2011 and it took a couple of months for the wee holes to stop. How much can I safely drain at a time?
Won't draining and refilling just remix the CYA and result in having to drain a lot more water overall?

 

[Smykowski]

There is no CYA in any type of fill water. When you drain any amount, you are dumping some CYA overboard, and the refill dilutes the CYA that remains.

Sent from my Exhibit II using Tapatalk.

 

[kimkats]

You will have to drain most of it BUT do it a small bit at a time just to be safe! It will take longer but in the long run will be better.

Drain 25% and refill. Let is mix for a while (I am not sure how long :| ). Keep the chlorine UP during this time to make sure to not have a swamp . Drain 25% more and let it mix again. THEN drain 25% and you will be at 75%!

Now if you are smiling right and the stars are all lined up you will have your CYA where you want it!

Keep the FC UP. Don't worry about the PH as the PH test is not good above 10ppm FC.

Good LUCK! You will LOVE being in charge of your pool!

Kim

 

[UnderWaterVanya]

You will have to drain most of it BUT do it a small bit at a time just to be safe! It will take longer but in the long run will be better.

Drain 25% and refill. Let is mix for a while (I am not sure how long :| ). Keep the chlorine UP during this time to make sure to not have a swamp . Drain 25% more and let it mix again. THEN drain 25% and you will be at 75%!

Now if you are smiling right and the stars are all lined up you will have your CYA where you want it!

Keep the FC UP. Don't worry about the PH as the PH test is not good above 10ppm FC.

Good LUCK! You will LOVE being in charge of your pool!

Kim

Sorry but this math does not work.

Starting with CYA of 180.
Drain 25% and refill now CYA is at 135... So far so good.
However the next 25% does not remove 45ppm (25% of 180) it removes ~ 34 ppm leaving 101 CYA rather than 90 CYA. Drain another 25% and again rather than a 45ppm drop you get a drop of ~ 25ppm resulting in a new CYA of 75ppm. Draining yet another 25% would give a new CYA of ~ 56 which is a bit higher than recommend but manageable.

In total using 25% at a time would take 4 separate drains to reach a reasonable CYA level whereas a one time drain of 69% would have given the same results. A one time 75% drain would have given a CYA of 45ppm.

However with a high ground water table the choice is clear - drain in smaller chunks based on the safe amount due to the level of water table. Yes it will take more water replacement to reach a reasonable level but that can't be helped unless reverse osmosis is an option.


-sent with Tapatalk 2

 

[kimkats]

I was just doing the 25+25+25=75 math. I guess the main messg is-little bits at a time will get the job done. Thanks for doing the correct math. That is what I LOVE about this site! Everyone is SO helpful and do not mind helping.

Kim

 

[UnderWaterVanya]

I was just doing the 25+25+25=75 math. I guess the main messg is-little bits at a time will get the job done. Thanks for doing the correct math. That is what I LOVE about this site! Everyone is SO helpful and do not mind helping.

Kim - no worries and I agree on the helpfulness - the problem with the math is that it makes a mistake that is pretty easy to make. Just in case it isn't clear to someone else why the math works this way I thought I would lay it out in a more graphical way...

Pretend for simplicity sake we have a pool that only holds 1,000,000 particles. Pretend this same pool has 180ppm of CYA or 180 total particles. This can be represented by 4 buckets of 45 particles each: [45][45][45][45]

If 1/4 (250,000 partcicles) of the water is replaced with 0ppm tap water: [0][45][45][45] we get 135ppm which is the expected result. This 135ppm then evenly distributes in the water to look like this: [34][34][33][34] (really 33.75 each)

If another 1/4 (500,000 particles changed total) of the water is replaced only 33-34ppm can be removed rather than the 45ppm initially predicted. After the water is replaced, the pool can be represented as: [0][34][33][34] or about 101ppm which evenly distributes to look like:[25][25][26][25]

If another 1/4 (750,000 particles changed total) of the water is replaced about 25ppm is removed and the pool can now be represented as: [0][25][26][25] which is about 76ppm that distributes evenly into: [19][19][19][19] buckets.

Once again we pull 1/4 (1,000,000 particles changed total) of the water removing another 19ppm and now the representation looks like: [0][19][19][19] about 57 which then redistributes to: [14][15][14][14]

If it is desired to get even lower CYA, and another 1/4 (1,250,000 particles changed total) was pulled off you would remove roughly 14ppm and end up with: [0][14][15][14] about 43 which then redistributes to: [11][11][10][11]

Contrast that with pulling 75% at once from the original water:
[45][45][45][45]... [0][0][0][45] which redistributes to: [12][11][11][11] giving you 45ppm with only 750,000 particles replaced.

This is mainly important when floating is not a concern and water rates are setup so that monthly use over a certain amount results in an increased price or where filling a pool is discounted. Either model might influence how the pool owner decides to replace the water. Knowing how this will play out in ppm helps the homeowner understand what the options are.

 

[Urodoc]

Thanks for the great explanation! :-D
I used the pump to "waste" the water down to the skimmer, then it stopped. :?
Old pool, main drain and skimmers on same valve.
So off to Northern Tool to pick up a 1/3 hp Wayne submersible sump pump and 1.5" hose.
Pumped around 7000-10000 gallons out in about 2.5 hours.
Now I'm about 2 months away from the break even point of paying for a pool guy vs. diy. :|

Refilling the pool now.
I'll let you know what the new chemistry is.


Thanks for all your help.

 

[UnderWaterVanya]

Thanks for the great explanation! :-D
I used the pump to "waste" the water down to the skimmer, then it stopped. :?
Old pool, main drain and skimmers on same valve.

You can try putting your vac hose in the skimmer and dropping it in the deep end. That should let you pull below the skimmer.

Refilling the pool now.
I'll let you know what the new chemistry is.


Thanks for all your help.

Glad to help.


- Sent using Tapatalk

 

[Urodoc]

I tried the vac hose in the skimmer thing. I have 2 skimmers. Had to try to plug the other one. Bottom line, no luck. So I bought a sump pump. It looks like I'll get plenty of use out of it.

Here's my new chemistry:

FC 0.8
CC 0.2
pH 7.5
TA 70
CH 220
CYA 120--So I brought this down a lot.

I'm guessing that I have to drain it 2-3 more times. It's getting there. I'm going to leave it to next weekend.

I live in Texas...not much need for snow or ice melt here. Does anyone know where I can by Calcium Chloride?
I just paid $21 at Leslies for 8 lbs. :?

 

[UnderWaterVanya]

I tried the vac hose in the skimmer thing. I have 2 skimmers. Had to try to plug the other one. Bottom line, no luck. So I bought a sump pump. It looks like I'll get plenty of use out of it.

LOL

Here's my new chemistry:

FC 0.8
CC 0.2
pH 7.5
TA 70
CH 220
CYA 120--So I brought this down a lot.

I'm guessing that I have to drain it 2-3 more times. It's getting there. I'm going to leave it to next weekend.

That result makes it appear that you drained about 1/3 of the water before refill. What is your target? The next time if you pull that much out again you'll have a CYA of 80, followed by 53 or so the time after that. 53 is quite managable and I would think that would be a good target.

 

[Urodoc]

Yea, I'm pretty sure I pulled a third off. I estimated based on time and gph on the sump pump, but I forgot about the first 5" I pulled off with the pool pump and I ran the sump a little longer. I'm planning on draining it 2 more times.

 

[Urodoc]

Here's an update.
Thanks for all the help. Pool looks great and I finally feel like everything is relatively stable.

Chemistry result today:
FC: 4.6
pH: 7.7
TA: 90
CH: 280
CYA: 35

I'm dumping in about a 121 oz of 8.25% bleach every 2-3 days and a cup or two of acid a week.

I ordered Calcium Chloride ice melt from Ace and had it shipped to store (we don't git much need fer ice melt in Texas). Took about 10 days, but it cost about $36 for 50 lbs. prior to that I bought 8 lbs for $21 at Leslies. Thanks for the tip I found in the forum. :-D