Not sure whether to post as a forum topic or just send to you -new at this.
Hoping you can help.
I posted this topic on another site and came across Chemgeek -he recommended i join TFP.
This I have just done and now send it to you.
I’m Based in the Pacific Islands.
Have an in ground pool measuring 10m by 5m by 1.6m deep = (approx) 75,000 litres.
Pool is concrete with a new quartzon plaster finish applied June 2007.
Pool has been great with no problems since June 2007 through to Sept 2009.
I then left the Island for 6 weeks.
The Manager in charge (for numerous reasons and with out checking with me) added floc to the pool as it was a little cloudy after bather use.
Applied the floc but left the filter pump on so it went through the sand filter.
Then turned off later & allowed to settle overnight.
Vacuumed the pool next morning to waste.
Most the stuff vacuumed but later in day he noticed it was back.
He tried scrubbing & vacuuming each day.
I arrived 9 days later to find my beautiful crystal clear pool of 2 years plus completely stained and looking very browny / yellowy /green.
Guests were arriving in 5 days time so decided to super chlorinate it as a form of bleaching the stain.
We only had available for this Dichlor granules
After 3 days of adding chlorine and scrubbing and backwashing to clean out the sand filter we finally got the pool back to its usual colour.
However, in the process of adding this amount of dichlor we had readings as follows:
Chlorine (DPD NO 1) = 0
PH= 6.8 or lower
Realised by 2nd day (after searching Internet) that the chlorine level was right off the scale –It had bleached the DPD tablet. Worked out approx 15ppm after diluting and then multiplying by dilution amount.
Worked on the PH & Alkalinity first.
Got both of these up using Soda ash dense (Sodium Carbonate) & PH Increase-(sodium bi carbonate)
First added 1kg Soda ash & 1 kg Ph Increase and ran filter.
Next morning readings were:
PH = 7.2
Alkavi = 80
Added another 500gms of Soda Ash & PH increase.
Next day (took longer for white cloudiness to dissipate) the readings were:
PH = 7.6
The Chlorine was reading high –still 10 to 15ppm
Ran the pump 24 hours
Next 2 days very hot & sunny
Still no real drop in Chlorine level.
Now received Pool Test Strips from overseas and able to test for more.
After researching Internet decided to try & tackle possible problem with High Cyanuric Acid.
Had reading of CYA = 150 to 300ppm.
Total Hardness = 500
Total Alkalinity = 120 to 140
Total Chlorine 5 to 10
Free Chlorine 5 to 10
PH = 7.6
Thought maybe with the high CYA reading that I was in Chlorine lock.
I had only Trichlor Tablets and Dichlor Granules.
First I wasted 33% of the pool water to waste.
I refilled the pool.
The tap water source had a PH reading of 7.6 and was double filtered and double UV treated before entering the pool.
This was the same water source I used in 2007.
Once it was filled I tested again.
The readings were:
CYA = 150
TA = 120
FC = 0.5
PH = 7.8
It was 11.30pm and I only had Trichlor & Dichlor.
I put 2 Trichlor tabs in floater hoping this would be enough Chlorine overnight.
In the morning the pool looked slightly unclear –almost a light grey haze.
Like it had had a few swimmers in i-just slightly hazy.
I sourced some Calcium Hypochlorinate Granules (first thing in morning) in order to superchlorinate the pool so as not to add any further CYA, while trying to increase the chlorine.
I added this as per instructions on bucket BUT
I decided to go with half the dose of 1.5kg to start with.
I dissolved it in warm water and slowly poured it around the pool edges.
On reflection I think I should have let it dissolve longer in the bucket and not poured all the undissolved granules in!!!!
Within 1 hour the whole pool went cloudy.
Several hours later I tested it and readings were:
CYA = 150
TA = 120
FC = 10
PH = 8.2
TH =250 to 500
Continued with filter and took readings this evening:
CYA = 150
TA = 80 to 120
TC =5 to 10
FC = 5 to 10
PH = 8.2 to 8.4
TH =250 to 500
Still Cloudy after 12 hours.
Decided to add MURIATIC ACID (POOL HCL) to bring the PH down
Based on Internet it recommended approx 1 to 1.5 litres of Muriatic to reduce PH of 8 to 8.4 to ideal range.
I diluted the acid in bucket of water and only put in 500mls acid.
This I poured slowly around deep end of pool with pump running and the bulk poured over area of inlet jet to aid in dispersing.
Basically, Am I on track and doing the right things????
Have I been doing things correctly?
For ease & convenience I have been using Trichlor tablets since 2007 as my daily Chlorine as required.
Usually 2 floaters with 1 tablet per floater lasting on average 8 days.
Some days has required 2 tablets per floater lasting 8 days.(When bather use higher or weather hotter etc)
The odd occasion I’ve added a cupful of Dichlor granules as a shock dose when water looks like it’s a little cloudy from high bather use.
I have never had to floc, nor have I used any other products such as algaecide, clarifier etc
BASED ON THE ABOVE and ALLOW EXTRA DOSING eg 4 TABS APPROX 40% OF THE YEAR AND NORMAL DOSING eg 2 TABS 60% OF THE YEAR.
TOTAL TABLETS REQUIRED PER ANNUM = 72 + 54 = 126 TABLETS. (45 DOSES IN TOTAL =360 DAYS COVER
I’ve now learnt from Internet of the effects of long term use of Trichlor & Dichlor with regards to raising the CYA levels.
It is not easy to source the variety of pool chemicals here.
Having sourced some Calcium hypochlorite I am conscious of its VERY explosive capacities and would rather not use it.
I thought based on my CYA still being high that I will need to waste the pool water AGAIN!!!
This time maybe wasting 50 to 75% (if not emptying the pool altogether!!!!) and then starting all over again.
Is it viable to do this and then start with a regime of Trichlor for 3 months and then daily doses of Cal Hypo (or another alternative not so DANGEROUS) for 1 month etc in an effort to have a clear pool for at least 4 to 5 years without having to waste water because of high CYA readings.
would regular backwashing for longer periods through out the year help to drain off the build up of CYA and refilling to dilute
Is it better to just waste water in one large drain off?
As well I’m nervous about using Cal Hypo because of the cal residue it leaves and the effects it may have on my quartzon plaster finish.
When the pool was established the manufacturers of Quartzon also supplied a liquid solution called “CAL-STOP”.
This comes in 5 litre containers & recommends 5 litres every 6 months or so to stop calcium extraction from the plaster.
I have added this when I am able to source it here.
On average I have managed to add this every 8 months since June 2007 and am due to add more very Nov/Dec 2009.
Would Cal Stop be similar to the residue left behind using Cal-Hypo?
I am a newbie to pools since 2007 and am keen to learn as much as possible.
I’m amazed how my pool was fine for approx 3 years and then one thing like floc gets added and not cleaned out thoroughly and then all other problems start!!!!
However, because of this incident it has made me learn more and I think I have a better understanding of my pool and water chemistry today than I did 3 years ago.
I have arranged for our freight container to come from New Zealand and realise this is an opportunity to source my own pool chemicals for at least a year or longer (if it has a good shelf life).
What chemicals would you recommend I purchase to freight by ship to the Islands given my pool history above and that I would rather not store CAL HYPO (if I can help it?)
I would prefer to remain with Trichlor Tablets/pucks (200gm) and work out a schedule or dosing regime that gives at least 3 to 4 years (if not longer) BEFORE having to waste large amounts of water (to reduce the CYA.
This may mean using another chemical in alternating dosages????
What do you think?
Finally, I have pressure from Guests wanting to use the pool.
Once the cloudy water clears up and the FC etc are OK only then will I open the pool.
How do you suggest I maintain the TC & FC over the next 9 days WITHOUT clouding the pool again using Cal-Hypo.
If I only add the daily dose of 350gms and make sure it is dissolved for several hours in a bucket and then pour it in at night keeping back any sludge or undissolved granules -will this stop the cloudy water effect? The instructions say to pre-mix in warm water.
I've read on Internet to pre-mix in cold water.
What do you think?
The other thought was to go back to Trichlor tabs for the next 9 days to maintain the Chlorine levels DESPITE THE HIGH cya just FOR THE LAST 9 DAYS (TO MAKE IT SANITARY FOR SWIMMING) Then the guests leave.
BUT I'M CONCERNED THAT A WITH HIGH CYA OF 150 TO 300 ANY TRICHLOR USAGE WILL JUST GO INTO CHLORINE LOCK ANYWAY(which is one of the reasons I went to Cal-Hypo in the first place apart from CYA levels).
WHAT DO YOU THINK?
Do you agree to empty the pool by at least 50% or 75% ONCE the Guests have left and refill again to deal with CYA.
ONCE THEY LEAVE i HAVE A 3 DAY WINDOW BEFORE NEXT GUESTS ARRIVE.
A WEEK LATER THEY LEAVE AND I HAVE A 3 WEEK WINDOW.
Apologies for the length BUT wanting to cover as much as possible to get to the bottom of this pool!!!!
Any help appreciated.