Pebbletech Infitiy Pool trouble

Sep 8, 2016
31
Chandler AZ
Hi, new pool owner here. I bought a place in April that has a pool, it's about 9500 gallons, pebble tech, Hayward 60 DE filter, vanishing-edge with a mostly clogged sheer-descent waterfall to return the water from the overflows to the main pool.

When I first moved-in, the water had been recently changed, but was very cloudy, filter pressure was at 36psi and would not go down with a backflush. I opened it up and the grids were totally collapsed, cracked, cloth bags torn. I replaced them and the pool cleared in about a day. The local poolstore told me that all I needed was some pucks (recommended 3-4 per week in 100degree AZ heat). You can guess what happened next, pool turned green, pool store then recommended Phosfree ($78), clarifier ($15), powdered shock ($5/#) etc. etc. etc.

I've gained and lost control of the pool several times over the last few months. The only time that things stay nice is when I added chlorine twice a day and specifically add it to the overflows for the negative edge every day (4oz bleach into each side). Even when the pool was not exploding with algae, it was taking a LOT of chlorine and if I didn't dose it twice a day it would rapidly drop to 0 and another outbreak would begin. I discovered TFP a while ago and have been reading and preparing. I got the TF-100 test kit and a ton of bleach and started a TFP shock last Saturday (FC:0, initial dose 3 gallons bleach).

My CYA was 58 due to the pool store guy telling me to just use pucks and the fact that the pool ate 40# of pucks 3-4months.

Chlorine consumption seems to have stabilized and I'm going to start letting it drift down. My overflows are relatively small, and in more direct sunlight than the rest of the pool. What I think is happening is that they consume chlorine MUCH faster than the pool itself, since they have more surface area relative to volume, are in direct sunlight & accumulate leaves they deplete their local supply of FC and get down to zero in the interval between when the pumps cycle and once the algae has a foothold there, consumption for the whole pool goes up and things spiral out of control. I have added additional trippers to the mechanical timers so that the pumps run twice a day instead of once (1-2pm & 6-11pm). The idea being that half-way thru the daytime, the water in the overflows mixes with the main pool water again to replenish its FC reserves. To test my theory, I checked the FC this morning at 9am, the main pool had drifted down to 20 from 24, but the overflows had drifted down to 19 (pumps stopped at 11pm). This seems to confirm my theory. TFP log attached. Any advice?
 

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Wow - your first post includes data from a TF-100 entered into Jesse's Log! I'm impressed! Welcome to TFP.

The theories can make for interesting discussions, but the end of a SLAM requires no guesswork:

- Pass the OCLT
- CC of .5 or less
- Clear water

It would be a shame to lose the progress you've made by quitting early.

CYA of 58. Pool store testing? I didn't have many doubts about adopting the TFP method, but my final lingering hesitation was believing that pool store tests are as bad as everyone says. They are! I recommend performing your own CYA test asap.
 
The LPS last tested the water on 8/13 and gave a CYA reading of 60. I tested on 9/4 with the TF-100 and got a reading of 58. Since I had already stopped adding pucks, that seemed about right that it might have come down a little bit. I have not tested it since then, since the SLAM instructions said that the CYA test is unreliable while slamming. Incidentally, the TF-100 came with calibration water which is supposed to yield a result of 50 and for me it gave 25 both times I used it, however, my actual pool water gave a result consistent with the LPS reading so I think that the calibration water that I got is off. I've been meaning to call the testing kit people about it.
 
I checked the chlorine in main pool and overflows again (pumps off). Chlorine in main pool down to 19, overflow now down to 17 (direct sun, 96deg outside currently). Just to be safe, I'll go by the highest CYA reading and boost the FC to 28 (up from 24).

Being an engineer, I decided to bust out some math. Clearly the overflows are going to have a lot more surface area relative to their volume, but how much of a difference? I had already modeled to pool water to calculate the volume since my pool is a weird shape and I learned here not to trust the LPS. In this case they were correct, 9,500 gallons give or take (I didn't model the stairs which reduce the volume a bit). The main pool has a volume of about 9759 gallons and 138,119 sq inches of surface area or 9.05oz pool water per sq inch of surface. Each overflow is about 212 gallons with 10,222sq inches of surface area, or 2.57oz of pool water per sq inch of pool surface. Assuming that the water is mixing around a bit (wind, brownian motion, etc.) the main pool has a chlorine reservoir that is 3.5x better than the overflows basins. This is why the disaster always starts in the basins. Here's the model of the pool water in the main pool:
 

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Nice model and interesting thought process. It sounds like solid reasoning.

Can take and share a pic of the pool and the overflows?

Once you get the water dialed in it will be easy. Keep up the SLAM until the above criteria is met. Your pool will look awesome and your wallet will thank you lol

:kim:
 
Thanks.

Here are some pics, the water is actually crystal clear now, but you can't really tell with all the fountains churning things up.

Oh no! I've already exceeded my photo quota, can't fit the overflow pic :( Ok, hosted it externally...

 

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Thanks, there are (4) spitting lion heads, one was clogged when I moved in. I dismantled the valve at the pump, duct taped my shop vac nozzle to it and with the vacuum running jammed a pipe snake into the lion's mouth a couple of times until the rock dislodged and ended up in the shopvac 40ft away. All lions work well now, but that sheer descent waterfall is a major pain. Those waterfalls are supposed to be fed from a filtered supply (mine isn't) and they're also supposed to have an in-line rock trap to catch pebbles and debris (don't have that either). So the waterfall is basically always clogged with small pebbles (from the pebbletech pool surface) and palm tree litter. Ongoing hassle. The pipes are mostly embedded in concrete, so no easy fix.

cheers,
c
 
^James, I know you got that from PoolMath but I've always wondered if there's not another residual factor at play because in Oct. each year before I close I've used pucks to both chlorinate and raise my cya and in my 23k pool, 16 pucks does not seem to add the 16 x 1.3ppm cya (20) that it theoretically should.

With that said, Vandal, if you've used the equivalent of 80 pucks (40 lbs) I agree that even a cya of 70 is suspiciously low so since cya is the foundation of maintaining a sanitizing level per the critical [fc/cya][/FC/cya], its worth rechecking and making sure you're following the CYA reading protocol correctly.

Are you reading waist high, quick glance versus "looking hard" for the dot, with your back to the sun? Here's a video to check against: Testing Cyanuric Acid with the TF-100 - YouTube

Secondly, I have a suggestion going forward with which several may disagree, but here goes:

Most installations are designed to do a complete turnover of water in about 8 hours. From your report, you're running your pump and filter 6 hours. (During a SLAM Process it should be running 24/7, btw)

I actually think that with the design of your pool and all the uneven depths and "catch" areas for debris you should at a minimum double down on your run time and in particular be running full on during daylight hours. Its the best way to ensure that the chlorine level is equalized throughout the system and will prevent pockets of organic collection.

This increased run time may mean you have to control ph more frequently, but perhaps the future addition of borates might help that aspect.

I realize that its easy for me to throw out suggestions for increased run times in a state where electric seems fairly cheap (Im in Michigan) but I seriously believe in this case it would help you maintain a trouble free pool ;)
 
How are you adding your chlorine now?

No filter to block trash and such for the waterfall would be a pain :( Is there any way you could just put s screen or such where the water leaves the basin? (I am thinking you have already thought about this but had to ask)

Some people have had good luck with a wire clothes hanger to clear their waterfalls and such.

It sounds like your idea to run the basin pump is showing that is how to go. Now to dial it in until it is purrfect.

:kim:
 
I wonder if you have "dead spots" where water is not getting adequate currents to get mixed well. Do you have a automatic pool cleaner running around to help mix the water, or lots of swimmers?

And regarding the CYA test, I do three tests carefully and with my back to the sun and take the average. IMO, it is not an exact test. You can pour the mix back into the bottle and redo it.

I'd be inclined to forget the Trichlor pucks until you get things dialed in then use them for maintenance - one less moving target. Add CYA until you are in spec.
 
Ok,it looks like I inadvertently exaggerated my puck usage a little. The tub is buried in the garage since I switched to bleach, I thought it was a 40# tub, but it's actually a 35# and there are 11 pucks left in it (1/2# ea). So I've actually put in a total of 29.5# of pucks, not 40# like I thought. It did add 3 or 4 1# packs of Leslie's powdered shock as well, don't know if those have CYA or not.

The pumps did run 24/7 for the first couple of days, since then I've been runnning twice a day, an hour in the afternoon to mix things up and the main run from 6-11. My chlorine consumption is way down, in the beginning it would take the chlorine down from an FC of 24 to 6.5 in a day (a loss of 17.5). After the final dose to 28, I haven't added chlorine in two days. It's currently at 13.5 at 8pm, down from 16.5 over 24hrs where my daytime temps are hitting 100+

By tomorrow, it should be to about 10 and I think that's going to be my new setpoint to give me some buffer for the areas that tend to go stagnant (overflows). What do you guys think? Is a drop in FC of 3 reasonable over 24hrs with 100deg daytime temps? Water temp is currently 84 as I've been running the mister to keep it cooler.

cheers,
c

- - - Updated - - -

I wonder if you have "dead spots" where water is not getting adequate currents to get mixed well. Do you have a automatic pool cleaner running around to help mix the water, or lots of swimmers?

And regarding the CYA test, I do three tests carefully and with my back to the sun and take the average. IMO, it is not an exact test. You can pour the mix back into the bottle and redo it.

I'd be inclined to forget the Trichlor pucks until you get things dialed in then use them for maintenance - one less moving target. Add CYA until you are in spec.

Yes, one overflow gets much worse circulation than the other. The waterfall seems to draw from both equally, but anything that is bypassed via the valve is only returned to one side, so that side get much more action than the other.

I'm in the shade and arms length with the cya, but I'm looking at it pretty intensely. I'll watch the vid and adjust my technique. The robot is always in the pool running around, I wish I had a tiny one for the overflows.
 
Do the test with your back to the sun. Let as much light into the side of the tube as possible. Hold the tube at the top with a finger and thumb. Pour it back and forth as often as you want to try different lighting. Many folks find that the test reads around 40, some folks say 50. Always round up your CYA to the next 10, it is only 1 more ppm of FC. And remember it is safe to swim with FC above minimum and up to shock level. There is a lot more room between target and shock level then there is between target and min.
 
Good morning, vandal.

I just want to confirm that you've actually finished the SLAM Process - meaning that the water is crystal clear, no more than .5 cc when you test, and that you passed the Overnight Chlorine Loss Test -- that was slightly unclear in your initial comments.

The chlorine consumption that you described as "stable" doesn't always mean the slam is "finished" -- the other three criteria combined do. To get the rest dialed in and maintain control require the "clean slate" of a completed slam.
 

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