I have kept naiad & filamentous algae under control with grass carp. The water always had a murky green brown color. Never clearer than 36", 18" in the summer. I listened to the fish guy, I know the pond better than him, & thought I should restock carp before the weeds had a chance to take hold. He said wait, MY mistake. Now I have a catch up problem, I have 10 carp per acre but much more naiad & algae than I want. What I have found interesting is that the naiad & algae have sucked out the nutrients that the micro organisms would use. Now I have the clearest water that I have ever had. Nice to watch what is happening in the pond. The BGs are on the beds I would rather have the abundant micro organisms for the fry. The pond is alway changing.

J.E. -- we have a term for that in our classes! Alternative stable states! Do the nutrients go to the phytoplankton, causing a bloom and decreasing water turbidity, which shades the bottom, and helps keep down the rooted, submergment macrophytes (higher aquatic plants) OR do the nutrients go to the submergent macrophytes, which results in very little phytoplankton, and that clear water! of course, physical turbidity such as colloidal clays in the water can mess up this concept, but it's nice for teaching. Hope you didn't mind me grabbing this teaching moment.

Dave:

As long as you are teaching, how do you balance a 1 to 1 3/4 ac pond that has very little or no submerged or emergent weeds, but a FA problem? Currently visibility is 30" or so with surface water temps in the mid 60's. I will be stocking Tilapia in a couple of weeks.

Every time I've treated the FA with Cutrine liquid, there is a brief period where the water clears (1-3 days), then the water will cloud for about 3-5 days followed by a good healthy bloom. A month after the good bloom, FA returns repeating the cycle. This is pretty much how the year goes unless tilapia are present. Please correct me if I'm wrong, but I suspect what is happening is the initial clearing is due the Cutrine killing the plantonic algae, the following cloudiness from the plants breaking down and releasing both nutrients and any trapped clay then the following bloom due to the newly available nutrients. Since adding aeration, this cycle has extended a couple of weeks and overall the clarity has increased by about 1/3.

So, to increase micro organisms you need to increase fertility. But, wouldn't adding fertilizer to JEC's pond likely only increase the existing weed growth? Wouldn't killing off the FA and macrophytes make those nutrients available to get a bloom going? What chemical would be best to accomplish this without hurting the spawn?

FA can be a headache. Especially the kind that grows in a blanket on the bottom. It is best to start early with fertilizing to get ahead. This is not always possible, though. If FA gets the jump you have to wait until water is warm enough on the bottom for herbicide to be effective. As soon as I think the FA is dead or dying I come right in and fertilize and stay on top of it so the water does not clear up. This can be tricky of course, and experience is helpful. This is assuming you have the proper alkalinity for fertilizing. If not you will fertilize future FA and who knows what else.

-HH

Sorry, Esshup. Just found the thread again. I don't have the experience to give you a good FA answer. Like you, I would have high hopes for the tilapia.

Thanks Dave. Rex will be here in a couple of weeks, I'll try to take pictures of the pond on a weekly basis to document the change in FA infestation without using any chemicals this year.

How many pounds are you stocking Scott?

I'm waffling between 10# and 15#. The Tilapia won't all be over 6", so I'm going to sort when stocking and put all the smaller ones in a cage and feed them like crazy. They would make for some really, really expensive fish food!

I want the stockers to survive predation. I'll also throw in some GSH and get some FH for the forage pond next door.