And I did not say, you stated plastic cover is better....you just state things slanted towards plastic...and I understand why.
"Natural Brush material adds to the nutrient load"
"Plastics have more surface area to grow fish food"
"Plastic like Rock improve water quality"
and that was just part of 1 post!
PVC is a Polymer created by linking large molecules to smaller molecules, the small molecule is VCM or Vinyl Choride, which is a known poison and cancer causing agent. Typically PVC still contains unreacted VCM...since '77 and the new specs you are allowed 2mg per liter to be considered safe!
Some studies show VCM and other molecules can leech under full sunlight in shallow water...due to the UV light...I have no firm data on this.
A christmas tree with all it's little branches and leaves will have more surface area and provide more natural benefits to the enviroment....but, it is used up quickly!
You can Aerate a small pond cheaply and easily, small ponds normally are fine with vegetation giving off oxygen, aerobic bacteria need oxygen also to break down nutriets etc, to convert into more oxygen.
You have surface and subsurface ways to circulate and Oxygenate water, that is more efficient than what PVC can do to improve water quality.
A small lake full of Natural vegetation or natural cover is not going to nutrient overload, without being fed by large amounts of Phosphorous from run-off, etc!
I use PVC in harmony with hardwood and other natural cover, due to the amount of acres we must cover, and the amount of time we have to do this, we cannot keep re-doing 2500 acres every 3-5+ years...if I had my own smaller, personal, backyard pond, I would think in a different way. PVC is a great choice for long lasting cover...period!
Thanks for the discussion....it's -7 degrees (without the windchill) and quite chilly outside. With over a foot of snow on the ground still.... Our lake is under 12-15 inches of ice and it will be April before I will be able to fish it!