New here with lots of questions,

To start with I had no idea a pond could be so much to worry about. We purchased a place 3 years ago in Northwest Alabama that has a 3 acre pond that was built in 2013. Was told it was stocked with LMB,BG,RES and GC.
When we moved in we went to local Tractor Supply picked up fish feed and started feeding. The next spring I learned about FERTILIZERS. My local co-op had Pond Perfect so I started that and was successful in getting a green pond with no problems. Last year in late spring (May I think) I started fertilizing again. Two weeks in nothing. So added more. A couple of days later our pond looked like a pool. It was aqua blue. Not green it was between sky blue and blue bird blue. Don’t think we lost any fish or we didn’t see any. After 3 or 4 days the pond turned crystal clear. We got County Extension guy to check water. I showed him pictures of our blue pond and he said he had never seen that before but had heard of it once from someone at Auburn university. His test recommended 5 tons lime per acre. May of this year the lime was added but I am scared to add fertilizer. I did for 2 years but now I have submerged algae in different spots to depth of about 6 to 7 ‘. When I showed him a sample of it he said it was Chara and recommended Diquat. Another agent said he didn’t think it was Chara but Diquat would kill whatever it was. Needless to say I am very hesitant to put anything in the pond now. As the summer has heated up the algae is dying and coming to the surface in small clumps, not a lot just a baseball size clump here and there. I do plan on adding some more GC (10 maybe). I would rather try that then the chemicals if needed.
The things I think I have done right is liming and this year changed feed to Optimal BG. They seem to really like it. I am hand feeding from the pier.
Would aeration help my pond? Shallows are 2 to 5 ft and the deepest 18ft. The pond is shaped kinda like a peanut.
As y’all can tell I am wanting to do something to help the pond along but really don’t know where to go from here. Any advice or suggestions would be greatly appreciated.

Welcome Rodo!

Chara usually has a skunky or garlic smell if you squeeze, crush, and/or tear it. The submerged stuff you mention that is floating up in clumps sounds like filamentous algae (aka FA). The first thing to do is positively identify the vegetations/algae. Pictures will help the forum to identify the types. These pics will need to be very clear and particular to get the best advise. It is helpful to take a clear glass baking pan with enough clear water (tap is fine) in it to allow a sample of the greenery to "fluff up". Put this pan on a white surface and get some photos to post. Using a very clear plastic bottle, jar, or baggie works well too (with a white background also).

I would not do any treatments without knowing what you are dealing with for sure. And, adding more carp should wait as well. FA is not a favorite food for carp unless it is a last resort and even then they may not do much about it.

In my opinion, aeration is a small tool in pond management and plays it's biggest role in increasing dissolved oxygen which allows for more fish mass to live in the pond. A quick web search on weed/algae control produces many hits of aeration sellers claiming it will solve all your problems, but that's just not true. It will help, but it's a small piece of the big puzzle.

I can not help with the water dynamics you are experiencing, but there a quite a few folks here that will chime in.

The extension guy was 100% wrong, Diquat will not affect Chara.

Get some cheap test strips for an aquarium and test the water for alkalinity. You want the reading to be above 40 for the fertilizer to work.

I don’t think it is Chara either. It has no noticeable smell at all. By the pictures I can find on line I think it looks like Nitella.

Before liming the pond was at 12ppm whatever that means and a month after liming I took a sample in and they said it was up to 24ppm and I just needed to keep it above 20. Is this correct?

I have tried to take some pics as Quarter Acre suggested and will try to post.
Whatever it is was bright green in spring and early summer but the heat seems to be having an affect on it. It’s not near as plentiful and more brown now with just a little green. You can drag a worm across the bottom now without it being completely cover.

Thanks guys working on some pics.
Will pic up a test kit tomorrow as esshup advised.

Rodo:

20 is a bare minimum, sort of like running your car all the time with the "low fuel" light on. Anything can push it below the minimum and that isn't conductive to keeping a bloom going in the pond. That's why I said 40, you have more leeway. Our alkalinity up here averages around 160-170 without us having to lime the ponds at all.

So I can plan on liming again next year or does it work in water like it does in soil? I have always heard it take at least 6 months for lime to really affect soil.

Finally got a pic of what I am dealing with. Put a dime in for reference.

Nitella and Chara are both forms of algae. Diquat will not work on them.

It won't hurt to do it again next year.