Water Balancing - Need opinions.

[ifmx4ever]

First Test Result using a brand new TF100 test kit!!! My second post to the forum. Great site and plenty of useful information. Wish I had come up to this site much much earlier - 5th year pool owner. Tired of spending way too much listening to pool store suggestions.

Test performed 06/08/2010 evening after sun down. No use of the pool by any member in the family.

FC - 13
CC - 0
pH - 7.2
TA - 130
CH - 510
CYA - 60
Borates - N/A

I had poured in a gallon of chlorine (10%) yesterday morning. My SWG is busted with damage to the cell and the power boards. Working on getting it replaced. I also have brown spot at different locations in the pool - size of a penny - not quite a perfect circle always. Any amount of brushing is useless.

Performed a overnight FC loss test and FC came down by 1 ppm and read 12 ppm this morning. Again no CC.

I am concerned about the high CH value. Any suggestions? Pool calculator suggests to drain 49% of the pool water and fill it with new fill water. Not sure about the CH on the fill water. Want to eventually get to BBB treatment and maintenance, but I think I have long ways to go.

 

[svenpup]

Welcome

...Want to eventually get to BBB treatment and maintenance, but I think I have long ways to go.

No time like the present. There is no reason not to start using the TFP principles now.


The only ways to bring CH down is either replace water with lower CH water or do a reverse osmosis (RO) service. There may be an RO company near you, as the tend to be in places with lots of pools and not a lot of water (AZ).

You can live with high CH as long as you keep your Calcite Saturation Index (CSI) in check. This would mean lowering your TA and making sure your pH never gets too high.

 

[ifmx4ever]

What is a good method to replace the water? I do not want to use the services of a RO company. More money to spend. I think the drain and refill is a viable option. Is there a good way to estimate the amount of water back washed in gallons? How would one go about draining half the pool? I thought the pool builder once mentioned that I should be careful not to let the water levels go down below the skimmer line. How does the water get to the filter / backwash outlet? Via the skimmer or via the in floor drains? Sorry too many questions.

Can I move forward with the BBB method in spite of my high CH values? CSI as per pool calculator showed something like Now: -0.18 and Goal: -0.51 with the comment - potential to become corrosive plaster?

 

[frustratedpoolmom]

Test your fill water for us, let us know if it's even worthwhile to replace water...

The draining issue probably has to do with exposing the plaster to the AZ heat/sun.

 

[dmanb2b]

Psst....your already BBB'g. Welcome to TFP.

The 1st step was getting the test kit - check

Next is understanding your water chemistry. Dealing with CH of 510 can be tedious, but is also manageable. If you keep your PH below 7.8 (target 7.4) at all times, the high CH should not cause you any concern and will likely not result in scaling.

On the dark spots...any chance you can post a pic?

 

[svenpup]

First off, you should test your fill water. There is no sense draining and refilling if your fill water has high CH.

When I had to drain 50% and refill because of high CYA I went out and bought a submersible pump. Don't let the pool pump(s) run dry, which will happen if you go below the skimmer level unless you can shut off the skimmer suction line and only draw from the main drain (depends on your plumbing setup).

There is no magic to the BBB (I call it TFP) method. The tenants are test frequently, know what your are adding, know why you are adding it, and where possible use low cost grocery store versions of chemicals. Thats it.

Your CSI is fine now, primarily because your pH is low (and I am guessing that your temp is low). With your high TA, pH will not stay low so you will have to stay on top of it.

You would never want to target a CSI of -0.51.

 

[PaulR]

Balancing with both high CH and a SWG in a plaster pool is a little tricky. It would be good to have CSI right near zero or a little negative with pH on the low side, so as it climbs you stay in the safe zone. I'm curious what targets you were using to get CSI of -.51? I played around with the pool calc a bit and there's quite a reasonable range of pH/TA values that work out nicely. Knowing your pool temp and salt number would help.
--paulr

 

[ifmx4ever]

Thanks to all who responded. Help me better understand. I am attempting here to respond to questions asked so far by all. Appreciate your time in helping me understand and resolve issues.

frustratedpoolmom / svenpup: Fill water shows a CH of 140.

dmanb2b: I have attached some pictures. I am hoping that these might give a clue.

PaulR: I took the numbers off the first post and plugged it into the pool calculator. Pool temp is at 82F and Salt level is at 4410.
The following values were used for the pool calculator. Could you use these and let me know if you get the same values for CSI. Not that I am doubting the poolcalculator, but just want some reassurance as to what I am doing.
Pool size: 12300 gallons

Now Target
FC 13 4
pH 7.5 7.5
TA 130 80
CH 510 260
cya 60 80
Salt 4410 4000
Borate 0 50
Temp 82

Results in a CSI of Now: 0.12 and Target of -0.51

-ifmx4ever

 

[svenpup]

Now that we have all the information I think I would leave the CH alone, or only drop it a little:

• Your target level of salt, borates, and cya are all driving the CSI down[/*:m:2nkinfeb]
• Your will want to keep TA low (maybe even lower than the 80 that you indicated) to counteract rising pH. Lowering TA also drives the CSI down.[/*:m:2nkinfeb]
• This means the high CH will balance the other CSI drivers and help keep the water balanced.[/*:m:2nkinfeb]
• If you were to drop CH to 260, as you saw on the pool calculator, your CSI will be in the corrosive zone. Bad! [/*:m:2nkinfeb]

 

[PaulR]

If you're looking at a 10% drain to get salt from 4400 to 4000, that would also bring CH down 10% (if you fill water has CH close to 0) or to 460. If we allow for CH 150 in the fill water, you'd get CH 475. So, if we say: pH 7.5, TA 80, CH 475, CYA 80, salt 4000, borate 50, temp 82, that yields a CSI of -.25 which is on the low side; pH could climb to 7.8 and still have CSI not go above zero. That gives you plenty of head room for CH and TA, which seems like a reasonable place to be.
--paulr

 

[ifmx4ever]

If you're looking at a 10% drain to get salt from 4400 to 4000, that would also bring CH down 10% (if you fill water has CH close to 0) or to 460. If we allow for CH 150 in the fill water, you'd get CH 475. So, if we say: pH 7.5, TA 80, CH 475, CYA 80, salt 4000, borate 50, temp 82, that yields a CSI of -.25 which is on the low side; pH could climb to 7.8 and still have CSI not go above zero. That gives you plenty of head room for CH and TA, which seems like a reasonable place to be.
--paulr

Thanks PaulR for your response. In fact I am going to have to replace the SWG as the equipment is now busted. I am awaiting deliveries. The new SWG will require a salt level of 3200 - which means I might have to drain some considerable amount of water about 21%, which might work to my advantage as well.

Let me know if it is right on my part to wait for the BBB process considering the fact that I will have to replace water to bring down the salt to recommended levels of the new SWG.

 

[PaulR]

In that case, don't fiddle anything until you're done with the drain and refill; it's literally money down the drain. At that point it becomes worthwhile to rebalance. And just use bleach as your chlorine source until the new SWG is up and running.
--paulr