Hi John, I got your message on the string algae...
You clearly understand what a Wildlife Pond is and are committed to that kind of pond. That's pretty cool.
The next step, and it will probably be on on going forever changing type view, is to figure out what kind of Wildlife Pond you want...and that's what you're doing now...deciding how to handle the string algae. The pond will keep throwing new things at you and the process is always pretty much the same.
The most basic, or you could say "true" Wildlife Pond is hole + water and stand back. But we normally do want to make adjustments and there certainly isn't anything wrong with that. I'm sure not a purest in any sense and consider humans to be part of nature.
IMO a "true" Wildlife Pond really needs to be pretty large, 30x30' maybe and a mud bottom. Could be a liner but still covered with maybe 1' of clay soil. I say this because the large area just seems to give nature enough room to do its thing. Like I've seen these fill 1/2 full of string algae, but never 100%. Like algae will start growing around the edges and slowly grow out toward the center. That gives time for other things to respond to that food source and they do battle. Plus temp changes (winter) help.
Smaller ponds are tougher. They can fill completely with string algae in a month or two. Some insects will love that, others won't. Frogs and turtles can have a problem with it as there's almost no open water. Duckweed can cover a small pond fast. One type of marginal can take over. Smaller ponds make it easier for a few types of plants to dominate. In bigger ponds I have seen cattails dominate.
These types of ponds (big and small) will fill in completely over time, as dead organic matter piles up, and become land again. That can happen faster in smaller ponds.
Some people are OK with all that but most people will want to make adjustments along the way. There is no right or wrong way, only what you would like at any point in time. One year you may be OK with lots of string algae, other years maybe not. It is interesting and informative to see a complete cycle of string algae, what it does as it decays, what lives in it at different stages. That does take maybe 3 years, but you learn a lot.
It is true that string algae, duckweed, etc., all add food to the environment. When growing but also, and more importantly, while decaying. But so do other species of algae. Hacking back string algae will generate more diverse life imo. So you'd be removing one food source but probably allowing other types of food sources (species of algae) to grow. That gets you more species of bugs.
The decision imo should be driven by your goals. In England it seems very popular to create Wildlife Ponds to support newts while in the US people seem to like frogs more. Weird why that is, but they have different goals which can drive how the pond is managed. A pond for birds (drinking and bathing) are popular and even ponds to maximize dragonflies, butterflies, etc. So owners may tweak the pond as needed to meet those goals.
Here's how I look at a small backyard Wildlife Pond, not saying you should do the same. I remove things that seem like excess. Totally subjective call. For example, I wouldn't want 100% duckweed coverage. Blocking sun blocks life. So I'd start pulling it to keep it at maybe 10-20%. I once pulled almost all the duckweed thinking the stuff grows so fast it would bounce back...but it didn't, it disappeared completely. These systems are surprising. What I learned was to see these system as much more sensitive than I did.
For ponds collecting a lot of leaves I pull some off the bottom from time to time, trying not to disturb the bottom too much so just with my hands. Not trying to clean the bottom, just trying to slow the build up. If chunks of muck start breaking off the bottom and floating around I remove that and will remove more muck off the bottom. I take it as a sign that too much (for my goal) organic matter built up too fast.
For string algae I pull it pretty hard. I don't consider it a great food source when alive, at least the stuff I see. Because I never notice insects really eating it much, or a population of an insect exploding to use the food. Makes me think it's not a great food. And it seems really slow to decay, so again, not a great food. I assume new algae growth is better food because I see that in other plants. So to me string algae isn't hugely productive and I don't mind scaling that back. A lot of insects do seem to live in the string algae so I think it provides shelter and some food, but it isn't exactly a power food imo. The big plus to string algae is it can really jump start a pond. So I'd allow it more in the first couple of years an hack it back more as the pond matures (more diverse life).
So to me removing string algae isn't going to hurt anything, makes life more diverse and speeds up getting to a more mature pond (lots of kinds of life). Plus it's easy to add better foods if you think the loss of string algae is impacting the food chain. For example you can add fish food (dog, cat food) even though you don't have fish. Lots of bugs love that food. How far you go is your call. Fish food will benefit some bug species more than others so you would be changing the system. But when you scale back the food those populations will crash which will feed other kinds of bugs so its all good imo. In large Wildlife Life ponds many people add manure and other fertilizer to kick start life.
