Pea Soup Pool

First off hello everybody.

Pool: In ground, concrete lined
Capacity: 50,000 liters
Filter: Sand (not sure of make)
Test Kit: DPD/Phenol tabs for chloring/ph + dip sticks (best i've got)
Local Water: Hard

When I opened it up:
Having taken the winter cover off (just a leaf cover really) the pool is green. When I first did this the water was pretty clear but there looked to be green algae on the bottom. Since I netted out some leaves etc a couple of weeks ago the water has been green. The pump has been running 24/7 since. Currently I can see about 3 steps down into the water.

1 week ago:
After testing the water about 1 week ago the pH was off the scale (over 8.2). Over the period of a few days I added about 4kg of ph minus (i think it is Sodium Bisulphate). Until the pH was down to 7.6. I've been backwashing every other day or so to stop the filter getting clogged.

Last night:
With the pH now at 7.6 last night i added 20 litres of 14-15% Sodium Hypochlorite.

This morning:
I was expecting the pool to be nice and milky this morning (dead algae) but it doesn't look much different.

Am i being impatient or am I doing something wrong? Any advice much appreciated.

PoolDoc note: Original poster is in the London, England area -- do not give North American specific advice!

Hi James;

There are several possible issues:

1. I'm not sure how you obtained 15% bleach, but if it was from a pool dealer rather than an industrial supplier, than there is an excellent chance it was 15% when shipped, but less than 8% now. The stronger bleach is, the fast it breaks down . . . and 15% breaks down quite rapidly indeed. I know that London had an unseasonably warm March, and if it was stored from last fall till you bought it, odds are it was NOT at label strength. That would turn your 60 ppm dose of chlorine into a 30 ppm dose of chlorine, or less.

Dry forms of chlorine are likely to have retained their strength.

2. You'll need to test your stabilizer level. I know you can't get the K-2006 kit -- they've been un-shippable since 9/11/2001, but you should be able to get the Palin or Lovibond tablet based test. High CYA could produce the results you have.

3. DPD tablets will not give you reliable tests in this situation. If your residual chlorine is above 10 ppm, tablets are likely to give a zero reading. You'll need to find some test strips that have syringaldazine pads (turns purple) or, better, a kit with OTO (turns yellow) drops.

Ben, can this poster still use DPD but dilute the pool sample--would that be more accurate than strips?

Janet

Not really, since he MAY have 60 ppm FC, with very high CYA. OTO will show dark orange under those conditions, but DPD will bleach out even at a 3:1 dilution. So he could use syringaldazine strips -- which do NOT bleach out -- as a present / absent test for chlorine, so he can tell whether a DPD zero result is a zero low, or a zero high, and work up a dilution that way. But by the time you dilute DPD that much, you'd be better off with OTO, if it's available.

Of course, it may not. The UK is somewhat notoriously more paranoid about work place dangers than the US. (There've been some stories recently about firemen unable to perform rescues because of extreme workplace safety restrictions, resulting both in unnecessary deaths, and in embarrassing situations where bystanders performed rescues as in the presence of 20+ fire and rescue vehicles and dozens of rescuers who sat on their hands!) Anyhow, OTO has been listed off and on as a possible carcinogen (if you drink it, or bathe in it!) so it may not be available; I don't know.

The bleach i got was from a pool store. Something akin to this: http://www.stuff4pools.co.uk/acatalo...les.html#a4070

This is the main kit i've been using (http://store.cascadepools.co.uk/pool...m=shoppingfeed).

In addition yesterday I tested with strips like this (http://www.amazon.co.uk/AquaChek-Fre...4922741&sr=8-4). I knoww they're unreliable but its the best i've giot at the minute.

Last night (before I put the chlorine in) these were the respective readings from the two kits:

Total Alkalinity: 100 (AquaChek)
Stabalizer/CYA: 40 (AquaChek)
pH: 7.6 (Aquacheck & Palin kit)

This morning I used an AquChek strip and the Chlorine part went a nice deep purple colour. Unfortunately i've run out of DPD No1 tabs (only got DPD No3) so couldn't get a reading from them too - i'l pick some more up tomorrow.

Does this help the diagnosis?

About the bleach . . . it probably HAS been stored since last fall, and it probably was NOT 15%. It's awfully expensive -- can you buy household bleach in London? What does it cost, and what is the strength?

I'm very familiar with that kit -- used ones very much like it for years. Palintest *does* have a stabilizer test that's reasonably accurate -- sort of a pain to get the tablet dissolved, but it works. If you look around online (there, not here) you can probably find one. If not Lovibond in Germany has very similar products. (I don't know what the relationship was, but once upon a time, it was very close and intimate.)

AquaChek is a US company, and as you say, the strips are unreliable, and the CYA test is the worst of the lot.

It looks like OTO is unavailable in the UK. That's not surprising. Dr Palin, who developed DPD, was from the UK (sorry, don't know if he was Brit or a Scot), and was behind much of the anti-OTO trash-talk in the USA in the 60's and 70's. He was very successful here, in making DPD the only 'respected' method; it stands to reason he would have been even more successful in the UK.

It looks like your best bit is something like this: http://www.1st-direct.com/lovibond-d...as_details.htm . For what it's worth, I purchased directly from both Lovibond and Palintest, and found Lovibond the more reliable company. It's all very pricy, but I gather that pools have been luxury only in the UK for years. I'm curious to see what will happen, now that cheap and functional Chinese Intex pools are making in-roads there, as well in the US.

If you could do me a favor, would you look in the largest and cheapest groceries you have around for each of the following:
+ bleach (sodium hypochlorite solution -- need price & concentration)
+ washing soda (sodium carbonate, soda ash . . . US "Arm & Hammer" brand may be available -- need price per pound or KG)
+ baking soda (sodium bicarbonate, sodium hydrogen carbonate, sodium acid carbonate -- again US "Arm & Hammer" brand may be present -- price per weight)
+ borax (sodium tetraborate decahydrate . . . may be present in Italian brand or US "20 Mule Team")

All these may be found in the detergent or household chemicals section.

Also, if you have any 'super-stores' like the super Walmarts, here you might look and see what they have. Since Intex pools are being sold in the UK, *somebody* is probably mass-marketing pool chemicals, even if they are just getting started.

This would help me, and will probably save you a pretty penny as well!

I'll have a hunt see if i can find any decent test kits. Surprisingly hard to find over here, even on the internet.

I've had a quick look on the Tesco (Walmart equivelant) website and found the following:

+ Bleach:
I did look last year at quite a few places for bleach. The problem i had was finding just pure bleach. The nearest I got was 'Domestos Original'. Ingrediants
Disinfectant: Sodium Hypochlorite 4.8g per 100g,<5% Chlorine Based Bleaching Agent ,Non-Ionic Surfactants ,Soap ,Perfume. This sells at about 2 litres for £2.50/$4.

+ Washing Soda:
Soda Crystals in the UK. "Contains Sodium Carbonate Decahydrate greater than 30%". Sells at £0.90/$1.50 per 1kg.

+ Baking Soda
Bicarbonate of Soda. Sells at £1/$1.60 for 0.2kg from Tesco. Amazon UK sell it for £5.0/$9 for 1kg

+Borax
Can't find it after a quick search. Looks like i can get 1kg of Borax Powder (Decahydrate) from Amazon UK for £8/$13. Or they have "Household Borax Substitute" for £4/$6.5 for 0.5kg.

Well, so much for that idea! Sorry.

Right, since posting last time i've maintained a chlorine level of about 10ppm using stabilized chlorine granules. The pool wasn't getting any clearer or milkyer so I decided to switch the pump off to see if it settled.

After vacuuming to waste last night (in the dark by the time i got home!) I re-shocked with 10 litres of liquid chlorine. I also added a little acid as the ph was at 7.6.

This morning the pool looks a little clearer (i can see the bottom step in the shallow end) however it is still definitely green, not milky.

Am i heading in the right direction?

Quote:

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Originally Posted by chill123

Am i heading in the right direction?

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CHill;

I'm sorry, but I don't know!

It's right about at this point that I often throw up my hands on threads from posters not in North America. You don't have a decent test kit, or trustworthy test results; I don't know what to tell you to go buy, and add, and so forth.

I have no idea whether your 10 ppm means 10 ppm (actually & exactly) or 10 ppm (that's as high as the strip goes, but really 50 ppm) or 10 ppm (but really 5 ppm).

The only thing I can tell you is that USUALLY, when the pool is still green, you need more chlorine. Once I years ago, I encountered algae that didn't die till I reached and held 50 ppm of chlorine -- cya was about 50 ppm. But, because there is so much I don't know about your pool, I'm going to stop short of recommending that you add more chlorine. That's PROBABLY what you should do, but I don't know.

Does anyone know of any decent test kits available in the UK?

I called a couple of local pool stores yesterday and after some questioning discovered that their testing of water is no more advanced than mine! I seem unable to find what looks like a decent test kit for anything less than about £400/$600!

Could you not order the Lovibond kit I linked? £145 is not cheap, but it's a lot less than what you're reporting.