Checking my action plan

[AussieSwimmer]

I am back to our pool after an extended absence. We had a young helper regularly cleaning the filter, but no chemistry was maintained as it turned out.

The 24,000 gallon pool is VERY green. Worst I've ever seen, and I am wondering if it's beyond recovery?

Test results for now :

pH >/= 8.4
TOTAL ALKALINITY 80
Residual Chlorine - ZERO
Stabliizer 30-50

I think what I should do is :

1. Adjust pH using muriatic acid
2. pre-treat with 'Green to Clean' (or 'Yellow out) - I have both here, include physical brushing around the liner wherever possible.
3. Begin a cycle of shock treatments, and watching/correcting pH while I do this.
4. Keep cleaning the cartridge filter, while running the pump on a 24 hour cycle.

Would you advise of any adjustments to this strategy?

[Denniswiseman]

You need to Slam (Shock Level and Maintain) with relation to Chlorine / CYA Chart and Recommended Pool Levels

Use these common products to balance your pool
Liquid chlorine (sodium hypochlorite or plain bleach)
Muriatic acid (hydrochloric acid) to lower pH and TA
Bicarbonate of soda to raise TA
Aeration will raise pH only
Soda ash will raise pH and TA

Your shock level is relevant to your CYA
A CYA of 50 requires a maintained shock level of 20. You may want to dilute your water to reduce the CYA
Excessive CYA renders your chlorine ineffective and you have to use more to get the same sanitation
For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm
To reduce your CYA you have to do a partial drain and refill
Continuous use of Trichlor/Dichlor will raise your CYA which means you have to raise your chlorine level as well

A CYA of 30-50 indicates you are only using dip sticks
Test strips are commonly called guess strips
You really need to get yourself a decent FAS/DPD test kit (Taylor K2006c or TF Testkits TF100 in the states) to get accurate results as maintaining an appropiate shock level means testing quite often during the day and not just dumping shock in and thinking "that's it"

[AussieSwimmer]

Dennis, thank you again. I attempted to post a reply yesterday, but apparently it did not 'stick'.

A few follow up questions, all to do with a 'super-green' pool. This body of water is at the point where you cannot see the 2nd step underwater.

1. When aiming for high levels of free chlorine, would you recommend a simple sample dilution protocol so that we can meet the testing range of the test kit? What I am finding right now, with a test kit that reads up to 5 ppm (DPD test), is that diluting the water sample 1:4 or even 1:5 produces unclear results - the colors are not distinguishable from the undiluted sample.

2. Is it possible that this body of water is beyond recovery? I'm doing multiple filter cleanings per day, but the filter looks puny when I consider the total possible burden of algae in a 24,000 gallon pool. I think I need a truck-mounted industrial grade centrifuge with continuous processing here!

3. Is it okay to start out by only focusing on free chlorine, until I have the situation somewhat under control? Or should I simultaneously be attacking other chemical parameters that are out of whack? eg : total alkalinity is very low, calcium hardness is low, phosphates are very high and pH is somewhat low.

Thank you again for the great information. - Grant.

[Denniswiseman]

Forget about any adjustments to the water chemistry untill you have the algae under control
It maybe better to invest in one of the kits that I mentioned earlier to check your progress
Get a load of Liquid chlorine (sodium hypochlorite or plain bleach) to start your SLAM (Shock Level and Maintain)
When the pond clears pump the dead algae to waste if possible

[AussieSwimmer]

Thanks again Dennis. I may have a pool that cannot be recovered. I'm clearing the filter multiple times per day, and a spot check yesterday (local supply store) showed 21 ppm free Cl. You can certainly smell it! I am not however seeing any change in visibility in pool water. I am beginning to suspect that the total burden of growth is now just too high.

I will however ignore the other chemistry parameters for the moment. I suspect that some of the test results would be of questionable reliability in any case.

Of the 2 test kits you mention, I see that the TF100 has a 3rd available test for various forms of chlorine. Does that make this kit slightly better than the Taylor 2006c?

[Denniswiseman]

I'm reliably informed that the TF100 is better value but don't ship out of the states
You can't smell chlorine, it's the combined chlorine that you can smell
The difference between total chlorine and free chlorine is the combined chlorine
Emptying it out with a liner could be problematic
People have recovered from a pond to a sparkling pool
I would be inclined to follow the Slam protocol to the letter
A net on a pole will remove a lot of residue from the pool floor

[AussieSwimmer]

Good morning everyone,

I hope your weekend is off to a great start. I am celebrating, with thanks to Dennis, a full recovery of pool water that I had pretty much written off as unrecoverable. (it was BAD). I wanted to take a moment to write a note of encouragement for those in a similar 'way behind the curve' situation. A few comments :

- I now understand that the recovery involves a repetitive 1-2 punch of chemical treatment and physical removal. This means a LOT of filter cleanings (cartridge in my case, which I can now recycle and return to the filter unit within 10 mins. You'll also get pretty quick, by way of repetition. I prop the cartridge up slightly off vertical on an outdoor metal chair, and blast it with water between the pleats, rotate, repeat. I get it 'good enough' rather than perfect.).

- Clearing the main drains/surrounds involves guesswork initially, but Dennis had it right - use a pole with net to see what you can pull out of the bottom, to begin with. Your main drains may well be choked with material that has settled against them, which is going to slow the whole process, and I imagine make the pump work harder than it needs to.

- Eventually I struck on the idea of running a brush head with vacuum line to skimmer basket, but instead of using a pole, I wore goggles and spent probably 2 hours duck-diving and clearing as much of the bottom (brushing and general vacuuming) as I could on a breath of air. I'm probably building some fitness doing this! An enjoyable exercise on a hot day. By the way, free chlorine levels had subsided to the point where it was tolerable to be in the water.

- Don't try netting the dead residue on the bottom. It looks like dust, and you'll quickly discover that all you are doing is stirring it up, making it harder to pick up by vacuum.

- Final steps for me are to make sure I have brushed the entire liner - I want to make sure that there isn't residual algae available to re-seed the pool the moment the chemistry drifts off. After that, one more go around on the chemical parameters, and then on to 3 other problems I have been wrestling with for at least a year now - inoperative control system, badly situated equipment, and liner drooping in a few places (separate posts to follow. These are going to be even harder to solve than the water situation).

Good luck! - Grant.

[Denniswiseman]

So glad we have helped you on your way to a sparkling pool