My very first pool chemistry test

[Cetanorak]

Just purchased a home with a pool that had been maintained by an older gentleman who dropped chlorine pucks into the skimmer. The 3" tablets are composed of 99% Trichloro-s-triazinetrione.

Today I ran my first Chlorine OTO, pH and then FAS-DPD & CYA tests.

Chlorine OTO was off the charts orange. pH 7.8.

FC = 14.5ppm, CC=0.5ppm, TC = 14.5ppm

CYA - dot was obscured by the 100 line, so perhaps much higher.

Do these chlorine and CYA levels add up given that the pool has been maintained longterm with chlorine tablets?

I aim to do the full TF-Pro series of tests soon, I just wanted to get a quick basis for where I was at. I know that extremely high CYA levels can only really be remedied by partial drain/refill. As water evaporates (very hot in Texas right now) should I just continue to fill with fresh water and only add liquid chlorine to see if things balance out at all?

 

[DrewLG]

FC = 14.5ppm, CC=0.5ppm, TC = 14.5ppm

CYA - dot was obscured by the 100 line, so perhaps much higher.

Do these chlorine and CYA levels add up given that the pool has been maintained longterm with chlorine tablets?

Yes, absolutely.

I know that extremely high CYA levels can only really be remedied by partial drain/refill. As water evaporates (very hot in Texas right now) should I just continue to fill with fresh water and only add liquid chlorine to see if things balance out at all?

You should stop using the tablets, yes, and use liquid chlorine instead. At some time in the future you may wish to install a salt-water chlorine generator so you can stop adding chlorine manually.

CYA above 100 is hard to measure accurately, so very high CYA makes it hard to calculate the appropriate FC level to keep your pool clear. And if you happen to get an algae bloom, very high CYA will make it difficult/expensive to raise the FC level high enough to kill it. So consider doing a partial drain/refill or other method of water exchange soon (but read about draining dangers first; it can be dangerous to drain using your filter pump, and it can be dangerous to drain while the air temperature is high).

 

[Mdragger88]

Since cya is over 90ppm You need to do the diluted cya test to get a better idea of the actual level so u can be sure to chlorinate appropriately FC/CYA Levels while u determine how u will exchange water & how much u need to exchange.
Step 8

CYA - Cyanuric Acid Test

Cyanuric Acid (CYA) is the chemical name for what is commonly referred to as Stabilizer … Read more…

www.troublefreepool.com

 

[Cetanorak]

Regarding draining, I have a plaster pool, temperatures have been near 100 daily for a couple of weeks. I have a cartridge filter and no 3-way that would allow for pumping/vacuuming to waste. Is my only option for draining to use a sump pump? I do have a spigot in-line between pump and filter, could that be used? I have read that if doing an equal exchange by turning off skimmers, putting a garden hose in a skimmer and pumping from the deep end with a sump pump, that there should be no turbulence in the pool that would mix the dense water with the new fresh water. That would mean that I couldn't use the main drain (rather than a sump pump) with the in-line spigot open, the returns would mix the water.

 

[Mdragger88]

Using a Submersible pump is the best option. They are a good investment since u have a pool that u can’t vac/drain to waste.
What u are referring to is the no drain water exchange.
The correct how to is detailed here

Draining - Further Reading

www.google.com

You didn’t list your ch - it may be up there too which would be another reason to exchange water.
Btw- Replacing water lost to evaporation doesn’t dilute/reduce cya, calcium, or salt.
As the water evaporates the cya, calcium, & salt remain only more concentrated due to the lower pool volume, when the water is replaced it just dilutes them back to their original levels.

 

[DrewLG]

Is my only option for draining to use a sump pump? I do have a spigot in-line between pump and filter, could that be used?

Sump pump is safer (and usually faster, although you'll probably be limited by your refill rate regardless). But you could use the inline spigot if you're careful to never let the water level drop below the skimmer.

I have read that if doing an equal exchange by turning off skimmers, putting a garden hose in a skimmer and pumping from the deep end with a sump pump, that there should be no turbulence in the pool that would mix the dense water with the new fresh water. That would mean that I couldn't use the main drain (rather than a sump pump) with the in-line spigot open, the returns would mix the water.

Yes, but you don't have to pump THAT much extra water even if everything mixes.

For example, say your CYA is 120 and you want to drop it to 80. If you could drain and then refill, you'd need 6700 gallons of fresh water. But if you just put the fill hose at one end and the drain hose at the other, and let the new water mix completely with the old, you'll need 8100 gallons. That's only 20% more.

 

[Cetanorak]

The only other hitch with a partial drain and refill is that I'm on a privatized water system (expensive) and we are in a stage 2 drought, so it may be frowned upon to run up a water bill refilling a pool. I will have to research. If I can't drain and refill right now, with sign of future rains, I'll just have to hope that the water remains "healthy" and feed the pool liquid chlorine instead of it's steady diet of trichlor.

 

[DrewLG]

The only other hitch with a partial drain and refill is that I'm on a privatized water system (expensive) and we are in a stage 2 drought, so it may be frowned upon to run up a water bill refilling a pool.

Yeah, I'm in the same boat (drought and $0.05 per gallon). My little neighborhood water company can't easily handle a big spike in demand, so when I bought the house I exchanged only a few hundred gallons at a time, once a week, until CYA was where it belonged.

 

[Cetanorak]

I've seen it mentioned that the PoolMath app can suggest % of pool volume to drain when CYA is high. How do you generate that recommendation?

 

[Mdragger88]

It just says to drain some water-
But it’s directly proportional- u want 50% less cya you need to exchange 50% of the water
The same goes for salt & ch roughly- although fill water may contain calcium so testing your fill water for ch should help you get a better understanding there

 

[Mdragger88]

The app doesn’t do this but the old poolmath webpage does

PoolMath

Discover the calculator behind the perfect pool, PoolMath. Dealing with pools has allowed TFP to become the original authors of the best calculator on the net.

www.troublefreepool.com

 

[Cetanorak]

I plan to do the diluted CYA test very soon to get a better idea of just how much water I may need to drain.

Regarding the need to drain a large amount of water, I have a gunite/plaster pool and daily high temps have been, and will be, consistently near 100 degrees for the foreseeable future. I have read that plaster should not be exposed to high temperatures and low relative humidity for long. I know that fewer large volume drain sessions are more efficient and economical than numerous small volume drain sessions.

I really do not want to attempt to maintain the status quo throughout the long summer, adding copious amounts of chlorine to keep up with the high CYA levels but do I have any other option than numerous equal exchanges? Can I run a couple of sprinklers to keep the plaster damp and do a larger drain?

 

[Mdragger88]

There have been some folks here who had success timing it so that it was nighttime when the plaster was the most exposed. You definitely don’t want it baking in the sun
Sprinklers are also helpful so you’re on the right track. Some people are lucky enough to have the pool come in the shade at a certain time of day so, so u can take that into consideration as well.
The no drain water exchange takes these problems out of the equation.
Knowing your true cya may really help u make your decision.
Be sure to maintain fc well above minimum for your (assumed) cya to prevent problems until u can exchange some water. 10ppm or above to be on the safe side FC/CYA Levels

 

[Deb04]

If I can't drain and refill right now, with sign of future rains, I

If you have some rains forecast, drain some and let your pool get filled by "free water." So, if you have 2 inches forecast, drain 2 inches.

 

[Cetanorak]

So I am officially in a stage 3 drought here. No rains in the forecast and I likely will be unable to drain/refill, to meaningful degree, for many weeks (perhaps months) due to water restrictions. I initially put the solar cover on to prevent evaporation, since water loss concentrates the CYA. The water temp is now in the mid-90's. As long as I'm keeping up with the FC/CYA recommendations, is there any reason why high water temperatures is dangerous for water 'health'? I'm not living at this house just yet, staying at an Airbnb an hour away why interior/exterior work is being completed on the home...so I can't yet test and manage the pool to the degree that the TFP protocol requires. I'm basically hoping to keep the water just happy enough until I move in next month and then I'll have to start doing small water exchanges and just eating the cost of high chlorine addition. The previous owner's pool guy has been made redundant, so there will be no additional trichlor added. I still haven't made it back to the house to do a follow-up CYA test use the diluted method (I very well could be dealing with CYA levels well above 100).

 

[Mdragger88]

Follow the FC/CYA Levels & stay well above minimum . At least target level or higher (it is safe to raise all the way to slam level if u wish) to buy u some time between doses. The cover should help u retain fc while u are gone.
.... "Min FC" is 7.5% of the CYA level
.... "Target FC" is 11.5% of the CYA level
.... "Shock FC" is 40% of the CYA level
Hopefully when u get moved in u can do at least some partial drains to make things more manageable.