I have a tank in Erath county that is near a dairy. About 4 years ago it started developing some kind of bloom/plant/algae, but I can't figure out what it is. I don't 'think' it is filamentous algae or any kind of hair-like algae. They are very small blooms probably a centimeter in size and will cover the tank for most of the warm months. It appears to have sucked all the oxygen out and i don't suspect any fish are in the tank anymore.

Here's the only picture i have. Sorry about the dead duck in the middle, it was shot, the algae didn't do that.

http://picasaweb.google.com/lh/photo/K5FsUQviPSAUBRnrN5srVA?feat=directlink

Any ideas?

not a very clear picture but it looks like water meal
http://aquaplant.tamu.edu/database/floating_plants/watermeal.htm

or try here

http://plants.ifas.ufl.edu/node/471

Watermeal can be difficult to control, Diquat or Reward is the best way to control it at this time of year or you can wait until spring and treat it with Sonar. Sonar is the best option for long term control.

Thank you! That is most certainly it.

So it's about time to do something with our tank. Right now the watermeal is gone, though there are small traces of it left on the banks. What would be the best recomendation at this point?

I do think I need to clear some of the junk trees from the banks as more of a long term plan to keep the leaves from falling into the pond, yes?

Should I treat with Sonar when the watermeal isn't currently present? Should I stock talapia? Can you do both? Will sonar take out submerged vegetation too? Currently the only problem is watermeal during the spring, summer and fall. I guess if Sonar will really take care of it for good, it's probably worth the expense, but if there are other cheaper methods, I would rather do that.

Any advice anyone has would be great. My goal is to have a habitable spot for fish for the long term again.

TIA!

Sonar has to be applied when the plants are present and actively growing. There is no getting rid of it for good, but Sonar usually gives 8 - 12 Months of control. Sonar does have some effect on rooted or submerged plants, all are effected differently and some are not controlled by Sonar.
You certainly can do both (stock Tilapia and Treat), in fact it's often best to take a well rounded approach as opposed to relying solely on one approach. You may want to treat the W.meal with Sonar this year and then give Tilapia a chance to keep-up with it the next year when it's better under control. In my opinion I wouldn't expect the Tilapia to control it but you could reduce the vegetation to a manageable level so that cheaper treatments could be used.

As far as the trees go it's a matter of opinion. Don't know how you're doing for habitat but you may want to think about using them for brush piles. Just a thought.

We usually kick off our Sonar treatments around April, basically you want your water temp to stabilize above 70F and have plants present. Sonar takes about 60 - 90 days to actually kill the plants but only has a half life of about 25 days so timing is critical.

If you decide to use the Sonar, or other chemical treatments, I would advise you to come back in the pond with Tilapia as soon as the chemical effects are worn out.

The Tilapia have a difficult time eliminating water meal(unless stocked in really large numbers) when its in full production...but if you get it under control with the chemicals, they (Tilapia) will keep it under control in most cases I have seen....a lot cheaper than annual Sonar treatments, IMO.

Regarding the trees, I would advise caution....all actions we take on ponds have reactions and sometimes unintended consequences. If the trees are relatively large with root systems that extend into the dam, then those decaying roots and stumps can sometimes leave a void that can sometimes cause leak problems in certain situations.

Take the trees out if you wish, but if they are large ones on the dam, I'd be real careful...also expect significantly increased summer water temps without that shade.

Thank you all for the info. I will wait until the watermeal starts to appear again, then hit it with fluridone.

Originally I thought the increase in willow trees that are dropping leaves into the tank were the main cause, creating the nutrients for the wm. The tank has very few areas where trees don't exist on the bank, as opposed to 10 years ago when it only had about 30% of the bank supporting trees (on the dam).

However, now it appears it's more likely due to the recent dairy that opened up next to us.

Maybe we will just clear the junk trees like the smaller mesquites and what not, and leave the rest.