First Season With Stenner

[Tomolena]

I'm preparing for a three week trip to Europe. I just set up my Stenner pump and poured 20 gallons of 8.3% Clorox Bleach into the tank yesterday. I tested the pump and observed that it moved one (1) quart of water in 28 minutes. I'm a little iffy on the use of poolmath for this, so I'm hoping that someone here can give me a little guidance.

By my guesstimate, I set the Stenner to run one hour per night to inject 2 quarts of bleach and thereby maintain my chlorine level somewhere between 2 and 3 ppm for the 3 weeks I'll be away. Does this sound about right for a 28K gallon pool in NY in April?

 

[pabeader]

According to Pool Math using 28000 gallons, you would need more like 3 quarts for 2.5 ppm. What is your CYA level?

 

[Jimrahbe]

Tom,

Using Pool Math tells me that 2 Quarts or 64 oz, will raise your FC by 1.5ppm in a 28K pool.

What is your CYA level, and how much FC do you loose each day?

Seems to me that if your FC in normally between 2 and 3, you are on the very edge of getting algae.

Please check out this chart... https://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock

Thanks,

Jim R.

 

[Tomolena]

CYA is around 40. TFT100 tells me around 45 and ColorQ indicates exactly 35. Going with the TFT I'm reasonably confident I'm in the low 40s.

 

[Tomolena]

...And I'm unsure of what my daily FC loss is. I'm not going to be around long enough to get a reasonable estimate on that. Going from memory of my readings from late summer last year, I was losing a minimum of 1.5 per day. But it was hot and sunny, and I had a serious CYA problem last year.

 

[Jimrahbe]

Tom,

With a CYA of 40 your FC should be around 5 to 7 with the absolute lowest you ever want to go as 3 ppm.

Jim R.

 

[Tomolena]

What's optimal for CYA? Always thought it was 30-50, so I shot for 40...which is where I am.

 

[Tomolena]

I more worried about over chlorination than algae, although algae is definitely a concern. What I'm getting from you guys is that I should at the very least run the Stenner for an extra half hour and get that 3rd quart into the pool.

 

[dsmith99]

Are you sure of your accuracy when testing? The 45MPH10 pumps .89 oz per minute, so it should take about 36 minutes to add 32 oz. I have found these pumps to be very close to stated output. That is almost 11 oz difference between your number and stated number over the course of an hour, that could be significant.

http://www.lockewell.com/pdf/45series.pdf

 

[Sfpat]

I wouldn't worry about over chlorination especially if no one is swimming in the pool. Better to err on the side of too much chlorine vs. not enough

 

[Tomolena]

Re: Are you sure of your accuracy when testing?

I'm reasonably sure about what I saw. I hooked the input to a water source and the output to a 1 quart measuring cup. Then I started the pump full speed and watched the clock. When the water level reached the 1 quart level, 28 minutes had elapsed.

 

[Tomolena]

Re: I wouldn't worry about over chlorination especially if no one is swimming in the pool. Better to err on the side of too much chlorine vs. not enough

I'd tend to agree, but I have a new heater. It's my understanding that heat exchangers can be subject to corrosion during protected periods of high chlorine. Please correct me on this if I'm overstating this issue.

 

[pabeader]

From all I have read and experienced, pH is the leading factor in heater issues.

 

[JoyfulNoise]

Bob's correct. Metal corrosion is dominated by pH and you'd need low pH (less than 6.5 at the least) to cause any significant corrosion. The presence of chlorine and chloride ions can accelerate certain forms of corrosion but only when the pH is low. Since you are injecting bleach and I assume your TA is a normal range, your water's pH will slightly rise with bleach injection.


Question - since you are gone for such a long trip, why don't you just purchase a bubble cover and cover the pool while you are away? Your chlorine loss will drop significantly and your pH will remain very stable since outgassing of CO2 will be all but stopped by the cover. Heck, the pool will also get a little warmer while your gone.

Another question - can you "incentivize" someone (family, friend, kid in need of cash) to come by and check on the pool while you're gone? All they'd have to do is look at it and shoot you a cell phone pic or a text message. If I were gone for 3 weeks straight, I'd at least want someone to look at it to make sure water isn't leaking somewhere....

 

[Tomolena]

Both good suggestions, but it's too late in the game for any of that. My pool builder has a maintenance service, so I'm probably gunna spring for that. Also going to bump my Stenner up to 2 hours instead of 1. I hate the timing of this trip...didn't give me enough time to evaluate everything.

 

[gary300]

Another thing to consider for such an extended absence is the PH level. How much acid do you need to add in a typical week to kept your PH in range? My pool still consumes about 1/2 gallon of acid a week to keep it at 7.5. When I go away for a week or so my Stenner keeps the FC steady. For the PH, before I leave I bypass my heater and add enough acid to bring the PH to 6.2. By the time I return the PH will have risen to 7.8. One other thing to consider is your water level. You do not want to loose enough water to evaporation to get the water level below the skimmer or bad things will happen to your pump.

 

[Tomolena]

My PH tends to drift downward, not upward, over long periods. But a heavy rain will knock it down faster. Good point about the water level. I'll bring it up to the very top of the skimmer.