Managing the Pool Water Quality

It’s been almost 4 months since I started to add water from the rainwater tanks into the pool, found a leak, and then pumped about 1,500 gallons back to the rainwater tanks, leaving about 5,000 gallons in the pool. And there it has sat while waiting about a month for delivery of the right materials to fix the leak and now for ‘muscle’ to manipulate the heavy material to be able to fix the leak. I’d hoped this would have been fixed one to two months ago but for various reasons it has not. This post covers the challenges of managing the water quality over these months.

Pool and Ponds As An Integrated Whole

The lap pool is approximately 40 ft long by 6 feet wide by 3-1/2 feet deep designed as an organic pool in that there is a pond at each end with the purpose of plants in the ponds to filter the pool water without using chemicals like chlorine or bromine. An air piping system will help oxygenate the water and move the water from the pool to the ponds and back again.

The ponds are approximately 2 feet deep. A gabion basket forms the barrier between each pond and the pool to both hold the air pipe system and hold the plants in the pond.

Filling the Pool and Ponds

Using a standard garden hose from the rainwater tanks just west of the greenhouse, water filled slowly so that I could smooth out wrinkles in the liner and check for leaks. Also I needed the water weight holding the liner on the bottom so I could fold the corners to alleviate a lot of the bulk. I ran the water during the day over the course of a week until it was about an inch deep in the west pond and held that level for a couple days. This meant the seam between the pool liner and west pond liner under the gabion basket did not have a leak.

Then I let the hose run overnight which moved the entire 5,000 gallons from the rainwater tanks into the pool. This raised the water level to about 9-12 inches below the full line.

Locating the Leak

The water level slowly declined over the next 12 hours or so until it settled at about 2 inches deep in the west pond. This meant there was at least one leak just above that level. Wet marks on the concrete on the other side of the pond wall confirm the location of the leak.

Although not confirmed with direct evidence, I suspect there may also be a leak in the seam between the pool liner and east pond liner.

Water Quality Testing

Coming from rainwater tanks where the ambient air temperature was in the upper 30s to upper 40s, the water in the pool was too cold for algae growth for the first couple months. Between the warmer ground temperature from below and the warmer greenhouse air temperature from above, the pool water temperature was in the mid-50s by early April and upper-60s by late May. The water was crystal clear until late May.

However, once the water temperature was warm enough for algae growth, without the pond plants and the air pipe system moving the pool water it quickly became stagnant with all the issues that flow from that.

Floating Pond Plants

Without water in the pond areas I couldn’t use plants to filter the water. But I added a few floating plants that quickly died. Water temperature was not likely the reason since they came from a nursery’s outside pond that was colder than my pool. However, the lotus plant was growing normally, sending fronds to the surface.

To set a baseline and to make sure there wasn’t something in the water that could effect the plant growth, I ran a series of tests using test strips. All results were ‘normal’.  

Bypassing the Air Pipe System

The air pipe system only works to oxygenate and move the water when the water level is above the top of the vertical 3” pipes. The system is designed with a single pump in the house crawl-space that splits to send air to each pond’s pipe system through a 3/4” pvc supply line, to a ¼” flexible tube to an air stone inside the vertical 3” tube.

I’ve been able to temporarily connect the pump into the ¾” pvc supply line for the east pond and put the air stones directly into the pool (instead of inside the 3” pipe) to produce bubbles and water movement in most of the pool. This has been sufficient to prevent mosquitoes breeding on the surface but is not sufficient to mix the water layers.

It did, however, confirm the single pump would not be sufficient to drive the entire system, including both pond’s circulation systems. So I’ve purchased a second, larger pump for the west pond that is feeding a ¾” pvc pipe directly into the pool.

Current Condition

Ultimately it has been a case of a bit too little too late. I’ve added 2 barley straw bales and waiting on liquid barley straw.

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