Anacharis. Egeria Densa. Brazilian waterweed.
I know this is what grows lush in the cement pond. For years now.
I wish it was native but Egeria Densa is commonly sold in the aquarium trade.
My mass started with a single sprig and has long provided a lush growth providing habitat, oxygenation and filtration.
The last couple years have been problematic.
The pond has always been crystal clear and the many different trees, plants and rushes have taken up the nutrients seemingly efficiently.
But recently, the last 2 years now, after a burst of Egeria Densa growth in the Spring the mass just quits growing. And the cement pond's water is turning green.
I had the water tested the other day and it reads...
GH 5 Drops
KH 6 Drops
I was told this is all good. The fish appear healthy as well.
I do not fertilize the water, and only feed the fish a can ( small soup can ) half full of Purina Game Fish Chow.
The pool measures 18' x 36' and averages 4' deep.
1 pump is running now and feeds a 6' cascading waterfall. In the Spring i plug in a 2nd pump to augment the riffle run and stimulate spawnings.
In the Winter i only run 1 pump, 2 hours a day, using a timer.
Why is the Egeria Densa dying? My guess the water is turning green is secondary because the Egeria Densa is NOT growing, thus NOT absorbing nutrients.
Possible contributing factors:
1) In the 8' bowl shaped deep end there is about 2' of settled silt. Several years ago i pumped much of it out but it has returned. I do not think this is a factor.
2) The pump chamber is provided water by 2 loops of perforated field line placed under a 1' to 2' gravel bed. About twice a year i have to vacuum the gravel bed using a plunge device and pump, purging the vacuumed silty water out into the yard. This has been a standard maintenance for years now. But over time it clogs more quickly, and if not monitored risks starving and burning out the pumps in the pump chamber. In response i have added a couple coarse filtered inlets directly into the pump chamber... thus less water is being filtered by the gravel.
Last Summer this occurred and i turned on the 2nd pump and the water seemed to clear... but i risk burning the pumps out if left unattended for a few weeks while i travel.
Any thoughts on why the Egeria Densa is not growing? Disease... i think not.
Does anyone have experience with native Elodea Densa? Perhaps it is a good time to switch to a native.
Beyond NANFA members is there a pond site that is recommended for solutions?