Hello, got a question for you pond experts please...

I live west of Houston, TX and we are in a two year drought.  Most ponds in my area are dry.  I dug a well to keep my pond full.(about an acre and a half)  Before I started filling the pond with the well I had nice hydrilla below the surface in a lot of my pond.  I have tilapia so it was under control and I really liked it.  I turned on my well and filled my pond back to the full level. Ran the well for about 5 weeks to get it full.   Probably added 25% to get it back to full.  For some reason now all my hydrilla is dying and decaying.  Can something in the well water be causing this?   Lots of scum is rising to the top of the pond.  I think it is the decomposing hydrilla.  I haven't noticed any fish kill but I sure hate to lose my hydrilla.  

Any ideas or have you heard of anything like this before?

Thanks

Couple of thoughts but I really don't know. I generally look for "What changed?" and the water seems to be the culprit in this case.

Have you checked the pond and well water for alkilinity and Ph? I have no idea what tolerance level plants can handle but a colder water change could possibly be a culprit. It might be safe to drink but have an adverse reaction for vegetation?

It MIGHT be possible that you did lose some fish since 95% of dead fish either sink or get eaten as they weaken.

Thanks for the reply Dave. I did not know that 95% of fish that die sink to the bottom. Do ponds need grass in them like hydrilla to keep fish alive? I have a lot of other structure in there.

Plus 1 on what Dave said plus adding that much water with very little oxygen in it can have adverse consequences to plants and fish I would think

Plus welcome to the forum

i added an aerator that I ran each night for the nighttime hours. I thought that would add the oxygen back to the well water. Is there a test I can by online that I can check my oxygen levels?

I don't think that was too much water added because it was done over 5 weeks so i figure the pond came up a qter inch or so per day in a pond that has 45,000 gals per inch or so. And you have been running diffusers to turn the pond over. It's is possible to have low DO in the hot summers in Texas
and running well water without it being aerated most likely does not help. So in the future i would run the well water across some rocks or something the will roll that well water for aeration to the well water. You can also run a ventury system in your water line to help aerate the well water. It is possible there is something else in the well water that needs to be looked at so i would suggest you send in a sample to TA&M for testing. Ponds do not have to have plants but it is better if there are some there, just not to many of them. You might want to check your fish population through fishing or surveying using a shock boat or running a sein. all information you can get will help you figure out what is going on.