Do you know how well the dye helps with controlling the temps?
I am NOT a pond dye expert. (Or even close!)
I have read a few articles that state the addition of pond dye does serve to keep the pond SLIGHTLY cooler. However, they did not give any good reasons.
I will speculate below, based on my ancient education in wave propagation and reflection versus absorption.
In the visible light spectrum, water most readily absorbs the longer wavelengths; red, then orange, then yellow. The green and blue light wavelengths penetrate the most, and that is why the ocean appear blue or bluish-green when you are diving.
When a dye is added and the pond now appears blue to an observer on land, then the pond is now efficiently reflecting the blue light, which otherwise would strike the bottom of the pond and be absorbed by the sediment on the bottom of the pond. (Which is the greatest cause of water heating.)
I also found this excellent article by Bob Lusk.
Lusk on Pond DyeHe says that the best pond dyes also reflect part of the UV spectrum. That is a significant portion of the total incoming solar irradiance, so reflecting part of the UV should also slightly reduce the pond temperature.
Finally, it turns out that one of the best ways to keep a pond cooler is to actually enhance the algal bloom. A nice green algal bloom reflects some of the incoming green light. Further, much of the other wavelengths are converted to glucose when the algae is forming sugar during photosynthesis. Energy utilized during photosynthesis is NOT available to heat your pond bottom or water!
If your water is very clear, maybe try some minimal pond fertilization??? If you can promote an algal bloom that will keep your pond cooler, and benefit the bottom of your food chain - which will eventually benefit your YP.
However, adding fertilizer may do more harm than good, if it eventually leads to more filamentous algae.
I would recommend reading some of the threads on water quality and adding lime and also some of the threads about fertilizing a pond. You can easily perform some of the water tests yourself, or send them to a state agency or a commercial lab. Once you get the results back, you should start a new thread with your water analysis, your existing fish, and your goals for the pond. At that point, some of our actual experts may be able to give you some excellent advice.
Congrats on getting your YP to take pellets. Good luck on increasing their size and getting them to reproduce! In good quality water, they can survive warmer temperatures than your location. Snipe used to grow state record YP near Goodland, Kansas under much hotter summer temperatures than you experience.
P.S. I also like the floating island concept. I can't see any downsides to adding those to a pond, unless they attract fish-eating birds. I believe there is at least one good thread on those islands.
