Pre opening chemistries: how to get to TFP values

[JayG]

Hi All,

I'm trying to take control of the pool this season and went out to measure where the chemistries are after a long, warm winter. I could use some help with current chemistries and how to move towards opening.

As of today:

Temp 54.5 F
pH 7.2
FC 3.5
CH 100
TA 60
CYA 90
Borate 0
NaCl 200

Water looks clear and clean. So not too bad. I drained out 12" at closing and I recently drained another 12" of snow and rain water accumulation. The tests above reflect values after the second draining. Based on end of season measurements, it's clear that there has been some dilution.

Near the end of last season I measured:

CC: ND
CH: 200 ppm
TA: 110
CYA: >100 (~120 if one extrapolates the scale)
NaCl: 600 ppm
Borate: 15 ppm

Seems some things were diluted by nearly 2-fold (e.g., CH, TA; borate and NaCl are rougher measurements, but they are also down). The guy who closed put some floating triclor things in. Does that account for why CYA hasn't dropped as much?

My questions are these:

1. Is there anything in my current values that I should address immediately?
2. If I want to bring CYA into TFP guidelines, I need to drain the pool down, yes? Is there any danger of draining it too much before refilling?
3. When I dilute the CYA, do I assume that CH and TA will go down as well?
4. Is there a necessary order to replenishing the various factors? What comes first? Borate, Ca, Cl2, bicarb? BTW, I plan to add boric acid from Duda (just ordered 110 lbs).

Thanks for any help.

Jay

 

[Richard320]

Aside from the high CYA, you look pretty good.

Yes, the trichlor pucks added CYA. They also lowered pH and TA because they're quite acidic.

If you intend to get the CYA down, do it now. There's no point in treating water you're just going to dump. The only caveat is not to drain too much at once if the ground is wet and the water table is close to the surface. You don't want to float the pool up and break the plumbing.

Once the water has been changed and has a chance to mix, you'll see that everything else has changed as well. Anyway, that subject can be addressed in a follow-up posting. If you test your fill water, you'll have a clue whether CH will rise or fall. pH and TA could go either way, depending on the water.

Get things all balanced properly before you add the borates. It's more difficult to adjust TA and pH once the boric acid is in the water.

 

[YippeeSkippy]

My questions are these:

1. Is there anything in my current values that I should address immediately? Your FC is too low, but you're a tad protected because the cold water slows any algae growth down enormously. Add some Calcium to bring it up to suggested levels for plaster pools. Drop some more water and lower your CYA some more (level varies based on if you have a SWG or not, or high sun exposure).
2. If I want to bring CYA into TFP guidelines, I need to drain the pool down, yes? Is there any danger of draining it too much before refilling? Yup, if you drain too much and live in an area with a high water table, the pool could heave. You could be cautious and either do it in stages, such as 1/3 twice, or up to 1/2 and fill right up again.
3. When I dilute the CYA, do I assume that CH and TA will go down as well? When you refill, the CH will be less, probably also the TA which is a nice number now. You need more Calcium already, the TA is easy enough to raise.
4. Is there a necessary order to replenishing the various factors? What comes first? Borate, Ca, Cl2, bicarb? BTW, I plan to add boric acid from Duda (just ordered 110 lbs). Ignore borates at this time you don't want to get into them until everything is stable for a while. You can raise pH if you want with aeration. Add chlorine first, baking soda if needed to raise TA, and Calcium after. I would suggest not putting the calcium in the same day as everything else.

Thanks for any help.

Jay

Are you planning on continuing to use the pucks?

 

[JayG]

Are you planning on continuing to use the pucks?

Thanks for the advice!

Pucks? No. I'm done with pucks as they have put our CYA into the stratosphere. As my sig indicates, I plan to go with a Stenner pump and an in ground HDPE 55 gal cistern for the bleach.

 

[JoyfulNoise]

Thanks for the advice!

Pucks? No. I'm done with pucks as they have put our CYA into the stratosphere. As my sig indicates, I plan to go with a Stenner pump and an in ground HDPE 55 gal cistern for the bleach.

Is that 55 gal drum based on what you think your bleach usage might be?

I'd be very wary of storing that much bleach in an underground tank. Bleach degrades over time so storing a large volume of it means its strength will change with time.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006

 

[JayG]

Is that 55 gal drum based on what you think your bleach usage might be?

I'd be very wary of storing that much bleach in an underground tank. Bleach degrades over time so storing a large volume of it means its strength will change with time.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006

The idea of storing in an in-ground cistern was to keep temperatures to around 65-70°F. I'm trying to make a kind of wine cellar for bleach. According to chemgeek's table, degradation is highly related to storage temperature:

http://www.troublefreepool.com/thre...bleach-over-time-by-storage-temperature/page2

If chemgeek's tables are to be trusted (and I have no reason to doubt them) I figure that I shouldn't lose more than 20% strength over the time it is used (e.g., 8-10 weeks), so that the last bit being pumped might be 10% rather than 12.5% assuming my below ground system stays around 65-70°f. But the average concentration over that time should be between 11-11.5% (or an average 10% loss of strength over the life of the fill). According to published literature, I'll do better in the first half of the season (temperature wise) than the latter but much better than having it above ground:

http://www.builditsolar.com/Projects/Cooling/EarthTemperatures.htm

I figure that for the convenience of filling up only twice or three times a season, I'm willing to pay for the small loss resulting from breakdown. If I insulate it properly with a 4' diameter collar of foam board buried a foot below the surface as planned (and given my site is in full shade), I might even achieve 60-65°C temps in my cistern. That would slow degradation even more than anticipated.

I know this is a maverick idea. Maybe someone has tried this and failed, but I haven't been able to find a link. Maybe it will be a bust, but worst case scenario...I can refill my tank more often with smaller amounts of fresh bleach. If that ends up being the case, I just won't take advantage of the full volume of the cistern.

I'll report back on the costs and bleach stability once I have it up and running.

 

[JayG]

Aside from the high CYA, you look pretty good.

Yes, the trichlor pucks added CYA. They also lowered pH and TA because they're quite acidic.

If you intend to get the CYA down, do it now. There's no point in treating water you're just going to dump. The only caveat is not to drain too much at once if the ground is wet and the water table is close to the surface. You don't want to float the pool up and break the plumbing.

Once the water has been changed and has a chance to mix, you'll see that everything else has changed as well. Anyway, that subject can be addressed in a follow-up posting. If you test your fill water, you'll have a clue whether CH will rise or fall. pH and TA could go either way, depending on the water.

Get things all balanced properly before you add the borates. It's more difficult to adjust TA and pH once the boric acid is in the water.

Thanks Richard. Very helpful.

 

[kimkats]

I can't wait to see the results of your bleach storage. Neat idea.

Kim

 

[JayG]

I can't wait to see the results of your bleach storage. Neat idea.

Kim

Thanks Kim! I'll definitely report back no matter how it turns out.

That said, I doubt that my approach will be a widely applicable advancement in pool sanitation. Our pool size is on the cusp of what a SWG can handle with alacrity, yet it is also going to demand a lot of bleach. Don't get me wrong, I love the idea of the SWG but I hear many more reports of algae problems resulting from SWGs unable to keep up/stopping working/ etc. to feel confident. I think it was Richard who wisely said that he never got an error message from a bleach bottle. That resonated with my KISS approach to life. I work with peristaltic pumps in my profession and trust their reliability. So, if I were to go with bleach I needed to find a way to make it less painful than going to Walmart every week to pick up another couple of gallons. We have a Ocean State Jobs Lot about a 30 min detour on my way home. I'll start the season with 25 gal of their 12.5% and see how it goes (Cl2 demand, stability, temp, etc.). Fingers crossed that I can make this work.