Erratic readings. ???

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dickeystorm

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LifeTime Supporter
Aug 7, 2010
143
Lake Jackson, TX
Hi all,

I'm in the process of SLAMing a friends pool. The pool is a 1970's vintage. It has a skimmer and main drain and 2 return eyes. There is an attached spa with a separate drain and 5 return eyes.

My trouble is the cya is running at 60 giving a shock value of 24 (28000 gallon). I dosed the pool to FC=27 after dark last night. This morning around 8 am it had dropped to 15 so we added 4 jugs of 8.25% bleach. The next reading a couple hours later read 30. This is higher than I expected. A subsequent reading gave an even higher result, 40, without adding more bleach.

I don't think I'm doing anything wrong but I'm confused by these readings. I suspect the pool is not mixing well due to only 2 returns. I also question whether the filter is filtering well because when I vacuumed this morning the pool clouded up pretty quick.

I have a related post in the Pumping Station forum. I hope to do a deep clean on the filter pending more info about the filter.

The readings so far

Last FC 40
CC not read
pH 7.7
temp 78F
CYA 60 (after dumping water, was 100, didn't get as low as hoped)
TA 180
CH 300

Thanks
 
You probably aren't doing the FC test quickly enough. When measuring really high FC levels you need to move through the drops fairly quickly or you can get false high readings.

One alternative is to do the FAS-DPD chlorine test with a 5 ml sample, instead of a 10 ml sample, and then each drop is 1 ppm of chlorine. That will halve the drops required and let you get to the end of the test much more quickly.
 
Hey!

Thanks for moving those over Dickey. :goodjob:

So, how's this going with the friend? Is he pretty receptive to your testing and suggestions? Sometimes people take to it and come around, sometimes not. I wish you the best of luck on all of it, and let us know if we can help.
 
It's going frustratingly slow. Still having some trouble with the readings. Last readings about a half hour apart were FC = 24 (added 3 jugs) >31 38 33 34. I'm using 5ml water for the test. I am not understanding why these numbers are fluctuating like this. I expected them to drop a lot more throughout the day. Water is better but still fairly green. I managed to vacuum a good bit to waste this morning but the latest vacuum attempts result in cloudy water. I'm suspicious that the sand filter may be channeling. I back washed for 3 minutes then rinsed and back to filter, pressure went from ~28 to ~13. Pressure had been running ~18-20 without rising very fast. I don't have a feel for how long this will take. My own pool responds differently and faster.

One big question I have is just how much dpd powder to use? I tend to put 2 heaping spoonfuls. Should I use more because of the high chlorine or is that irrelevant?

Latest view:
5-26-15 3pm.jpg

Thanks.
 

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This mornings readings, we took 3 reading from different spots because we're not sure we're getting good mixing. Vacuuming results in cloudy water, that doesn't seem right. I'll be opening the filter later to inspect and clean.

Spa FC/CC 36/0.5, shallow end 38/0.5, deep end 39/0.5 6:45 am

I think we've passed steps A & B now waiting on C :)

Reading taken ~11am 38/0.5, still green though. :(
 
It will take time to get the green out. Vacuuming will stir up sediment on bottom and hopefull pick a bunch up too. Lots of brushing even though you cannot see.

- - - Updated - - -

I heaping scoop of powder is enough. You cannot use too much.
 
It will also take a lot of time to get the cloudy out. This will not even happen in a few days on this bad situation.

One heaping scoop, not two. Especially on the 5mL test.

Keep hitting it, and keeping the FC up as you are. You'll get there, but it's going to be a good deal longer. Try to relax, let it take course. It took a while to get this way, and will take a while to clear.
 
Update:

I opened the filter and cleaned best AI could in the time I had, lots of dark green came out. That will be redone when time allows. I then closed it up and backwashed followed by a rinse and back to filter. Next I added about a cup of DE to the filter. Pressure started at 16 and went to 19, we'll see what the morning brings.

The readings were
2:40 pm FC/CC 36/0
6:30 pm 21/1 added 2 jugs
8:30 pm 24/0 added 2 more jugs

each jug gives a rise of 2.9 according to the poolmath assuming we have our numbers right.

Pics:

today 630p
View attachment 37103

Filter parts and flush
View attachment 37104
View attachment 37105

the battle continues...
 
It is a little late now, but you don't want to add DE to fast. You add it in a couple of additions until it rises 1psi. Then you leave it. You have to watch it close because it will raise quick. You may want to backwash tonight and add it again when you can watch the psi.

Your pics are not there. Upload them to photobucket then copy the IMG code for each individual pic and paste it here.
 
Patrick_B, and all, thanks for all the support. We are finally making some good headway. Still a little green but we can see bottom now! :whoot: I think our friend is seeing the light and is happy.

Today's readings:

10:30am 36/.5
8:30 pm 33/.5 sunny today

vacuumed followed by a backwash/rinse.

Today's big questions:

1. It appears that the algae is 90+% dead (slight CC). Why is it still green? Does that mean live algae still? That's my belief but I'm not sure. We're still treating it as such.

2. The BIG question! Why is this stuff passing right through the filter. The pic below shows the spa after vacuuming. It was clear when I started.



After vacuuming! Getting there.




My dpd powder is over a year old, as are the other reagents. The powder has turned a little gray. Maybe that accounts for the crazy readings. :scratch:
 
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