Winterizing 66,000 gal inground gunite pool in NW Minnesota

Ron Stordahl

Member
Sep 18, 2011
11
Our secure fenced 66,000 gal inground gunite privite membership pool is used for a maximum of 3 1/2 months in the summer in NW Minnesota. Attempting to operate if outside of that range is too expensive and it would be rarely used outside of those months.

After our season ends we pump out perhaps 1/3rd of the water to just below the lights, to avoid ice damage to them. We have also been advised that completely emptying the pool would be wrong as the ground water would place great stress on an empty pool. The pool is 45 years old and this has been the long time practice. We also vacuum all the water out of the plumbing and flush with RV antifreeze. To drain the plumbing is is necessary to partially empty the pool else the piping would be destroyed by the ice. Since we started using this procedure we have had no freezing issues with pipes and associated equipment.

Just one problem, for which I am asking for ideas: In the spring when we begin the start up we are faced with a real mess. The pool is full of leaves, which have stained the walls and bottom as well as algae stains. For years we have cleaned it up using a very high pressure water system with 3,500 psi pressure. This spring we used two of them to actually remove the paint down to the concrete, and after adequately drying painted with an airless system using chlorinated rubberized paint, resulting in a beautiful pool!

Any ideas on what might be done after the season ends to limit leaf staining and algae build up for next spring pool opening?

One year we did pour in a large dose of dichloro and floated some haystack black plastic thinking the leaves would accumulate on top of the plastic with the partially drained pool. It was only partially successful. The leaves found their way underneath the plastic staining the pool and there was still some algae. Perhaps the clean up was a little easier.

Maybe we could perfect this method. I am thinking of floating Styrofoam to support the plastic film for example.

So I am looking for ideas
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
8,920
Northern NJ
I take it you do not have a safety cover on the pool during the winter? The pool is drained halfway but open to leaves, dirt, and the snow?

I think your problem with floating any plastic sheets over the pool is they need to resist the weight of the snow load. And you need to secure the edges along the deck with sand bags. If you don't secure the edges water runoff will take leaves in from the sides of the pool.

To limit algae buildup close the pool later when the water temp will stay below 60 and open it earlier before water temp gets above 60.
 

Pool_Medic

In The Industry
Apr 1, 2018
953
Bangor Maine
A safety cover won’t work on such a large pool unless you have a lot of concrete to over size it. The oversized cover helps keep stuff from being blown under the cover and entering the water. I would recommend a winter cover with a custom built sandbag type perimeter to keep the cover from falling in. Yes, pumping off the gunk in the spring time is a pita but the water will be crystal clear under it.
 

Ron Stordahl

Member
Sep 18, 2011
11
Thanks for the ideas. I am considering trying again covering it with one time use low cost plastic film, but this time supporting it with floating styrofoam sheets and sand bags around the pool to keep it in place minimizing leaves getting into the water. I am hoping to avoid excessive staining which has required rather harsh cleanup damaging the pool paint. It takes about 25 gallons of chlorinated rubber paint at about $75.00/gal to repaint. We usually have to strip the paint with high pressure water and repaint on about a 3 year cycle. So extending this will be a cost savings. I am not anticipating that we will be able to salvage the remaining water...I expect it will be entirely too dirty. So I guess this will be an experiment, hopefully better than the failed one ten years ago.