Do I leave it as it is and close it or clean/slam it and then close it?

[lumpypossum]

Not sure if this is the best forum to post in but here it is :
Due to Covid we have just been able to return to south of France to our second home after closing the pool mid October 2019 but we are only here until start of November (we usually leave mid October and the pool has to be closed above 59F). The in ground pool (25,500 gallons) has been closed under a domed perspex pool cover for nearly a year (It has been hot in France this year so I can know the water temperature has exceeded 93F).
The water currently looks clear, there are no noticeable things swimming around in the pool, presumably they have all died and or left the pool as there are usually tadpoles, etc. in the green pool when it is opened in May. The readings are as follows: FCL 0.28, TCL 0.41, PH 8.1, TA 140, CH 155, CYA 19, Temp 83F.
The algae has coated the bottom and looks brownish and a rusty colour on the side walls.
My confusion is that the pool looks stable albeit a mess - should I disturb this equilibrium? Or will it be an even bigger headache next May??
It usually takes about 120 litres of 9.6% bleech to clear it every May, which is an acceptable cost if I am actually going to be using the pool for 5 months.
The pool does not have a liner insert and is just painted over something, don't know what but I am not too concerned over blemishes to the surface as long as it remains watertight.

I need some advice on my best options from the TFP experts that have been in this situation.

Thanks, Bob

 

[mknauss]

As long as it is not a mosquito breeding ground and you do not care how it looks, leave it. I am curious how you are adding chlorine. With a low CYA, high pH, and high TA, it cannot be trichlor, or your testing method is suspect.

 

[lumpypossum]

Hi Marty, thanks for the reply. Last slammed the pool in Oct 2019, before closing - no chlorine added since then. I was confused by the numbers and how the water appeared so clear and zero apparent wildlife. The test readings are possibly wrong as my La Motte test reagents are 6 months out of date so I will take a water sample to my local pool store and get another set of readings.

 

[mknauss]

If you have added no chlorine for that long, your test method is false. Pool Store will be worse, I would not worry about it. You will take no action anyway, unless you wish to completely clean it up, and then you need your own proper test kit.

As long as you are not having issues with mosquitos and do not care how it looks, no need to do anything. Deal with it when you want to enjoy the pool.

 

[lumpypossum]

I posted recently in Algae Prevention and treatment and wondered if a chemist could help me understand (in layman terms, if possible) what is happening in my pool. I don't understand how the water can be so warm and be clear with the total lack of chlorine, this appears to defy all I thought I had learnt from TFP. Is the chemical balance so bad that it has killed the algae and stopped any further growth - is this even possible. Will this bad chemical balance harm the surfaces of the pool if I keep the pool closed up and do nothing until May 2021?
Original post : Do I leave it as it is and close it or clean/slam it and then close it?

 

[Mdragger88]

I just looked at the other post & the water definitely doesn’t look clear or algae free. I am sure it being covered prevented some things from being worse . You added no chlorine when the temp was above 65F & algae grew exactly like TFP warns. As marty said in the other post just cover it back up if you’re not ready to open & slam . Perhaps if u open it before the water gets above 60F it won’t take so long to do then. If u can, throw some of those mosquito dunks in there. Your neighbors will thank u. If it regularly is in this condition or worse I doubt it will harm anything provided you winterized properly last time.

 

[Texas Splash]

I built a water garden a few years ago and stocked it with large goldfish. The water used its own ecosystem and filtration (through moss and such) to keep the water crystal clear. SImilar to what you have going on there. That did not mean however that it was sanitary for human use. I suspect your pool has something similar going on. As soon as a brush touches that bottom, it will be a cloudy mess. Whether or not you wish to tackle the SLAM Process now or wait until next spring is your call.