New Liner, New Water and a New Plan

[nicjamaica]

New to this Forum.

Bleached out a 2 year old liner with a massive Trichlor+CYA assault last year. Never again.

New vinyl liner just installed and filled with city water. Just fired up the pump and backwashed the filter (new sand last year). Holding 19psi with great flow.

Waiting on a TF100XL so picked up a cheap kit and had the locals do a water test. My results were pH maxed at 8.2 and Total Chlorine at less than 1 (very faint indication if at all).

Pool store results:

Free Chlorine 0
Total Chlorine 2
pH 7.8
Total Alkalinity 100
Adjusted Total Alkalinity 100
Total Hardness 80
CYA 0
I assume 0 Borates
Water Temperature 70 Degrees

I'd like to use liquid bleach this season but I have a couple of questions.

I have a pound of granular CYA and 30+lbs of granular Dichlor in inventory. Can I use these to start the chlorination/stabilization process?

Should my first step be to adjust the pH?

I'm going back to the Pool School to study ALL the information.

 

[Bama Rambler]

You can use the Pool Calculator to figure out how much Dichlor you can use before the CYA gets to where you want it. It'll also tell you how much to add per dose to get your FC where you want it.

 

[nicjamaica]

Day 4

FC 3.5
CC .5
TC 4.0
pH 7.5
TA 90
CH 100
CYA Not registering yet. Having added 44oz of Dichlor at this point (over 3 days) it should eventually test at 9.5.

Any cause for concern with the above readings?

Does it make sense to add the 16oz CYA at this point (via sock method) to boost the CYA another 6.8ppm (per Pool Calculator) and continue with the Dichlor for awhile? At what minimum CYA level would you discontinue the Dichlor and begin with the 6% Clorox?

I have not shocked the water. The water is crystal clear. Perhaps a shock treatment with the initial Clorox application?

 

[Bama Rambler]

You probably won't be able to read a level of 10 ppm CYA or less.
I'd target about 40 ppm CYA.

How much Dichlor do you have left on hand? I'd keep using it if you have a lot on hand. If you have just a little, I'd start with the bleach and add the CYA independently.

 

[nicjamaica]

Is there any meaningful correlation between filter flow rate into the pool and backwash flow rate or the Rinse flow rate? On Filter setting the gauge indicates 19psi, on Backwash the gauge indicates 10psi and on Rinse the gauge indicates 10psi (Waste shows a barely moving indicator bouncing off '0' so I assume no restriction). All are plumbed with 1.5'' PVC. The return line feeds both returns presumably through a 'Y' or 'T' fitting.

Just wondering if I could calculate actual (reasonably accurate) filter flow based on easily measurable backwash or rinse flow.

25# of Dichlor remaining + a 1# bag of CYA. I'll get the CYA in today targeting 40ppm. I can use the Dichlor for A/C condensate drip lines so i'll get started on the bleach this evening.

You have a very understandable approach. Takes all the mystery out of the equation. I actually look forward to testing the pool water when the results are somewhat predictable.

Thank you

 

[Bama Rambler]

You can't figure the flow rate based on backwash or rinse readings. The plumbing is completely different so they won't correlate to flow into the pool.

Once you're running normally you can post your plumbing and equipment specs and the filter pressure and maybe Mark (mas985) will give you a hint as to what your flow rate is. But let's not worry about that right now.

I'll get the CYA in today targeting 40ppm. I can use the Dichlor for A/C condensate drip lines so i'll get started on the bleach this evening.

That sounds like a plan. Just be sure to account for the amount of CYA in the Dichlor you've already added. Once you add the CYA, figure it's in there after 24 hours and adjust your target FC to account for it.

It would also be a good time to run an OCLT to make sure you don't need to shock.

 

[nicjamaica]

I lost slightly more than 1ppm FC last night. Assuming 9.5 CYA from the previous Dichlor (44oz into 17,500 gallons) should I target 6 for the Chlorine Shock value? I seem to fall below the CYA/Chlorine chart.

 

[Bama Rambler]

I'd use a shock level of 10 ppm and test and adjust back to there as often as you can.

 

[nicjamaica]

Will do.

Dichlor or bleach, does it make any real difference at this stage? I'm accurately tracking all Dichlor applications and adding the CYA bump to a running total.

 

[Bama Rambler]

It doesn't matter and since you have a lot of dichlor on hand I'd use a good bit of it up now.

 

[nicjamaica]

30 days on the new liner.

FC 4.0
CC 0
pH 7.8
TA 80
CYA 40

The pH seems to drift upward from the targeted 7.5 to 7.8 or above over 4 or 5 days. The return jets make significant swirls in the water but don't typically break the surface. Could this be responsible for the increase? The MA doses to counter the pH drift may have lowered TA from 90 to 80 over the last couple of weeks.

I want to add Borates/MA this weekend. Should I be concerned about the 80 TA level as it is on the lower end of the suggested scale. The Borate/MA application should raise TA slightly and the pH could then be raised with aeration, if needed, correct?

The water is 80 degrees, crystal clear and in full sun 9 hours a day. I'm running the filtration sysyem 12 hours per day and adding a predictable amount of bleach every evening (per testing results).

Thanks for all your help.