Question
QUESTION: We have a 12' by 18' pond that is about 6" deep with plants at one end and 18" deep at the other with water lillies. The pond is 4 years old and has always been extremely healthy with frogs, mosquito fish, salamanders and snails all thriving. I have always kept the green string algae under control with ALGAE FIX and manual removal. We had our well water treatment upgraded a couple of months ago and the new system has a much higher ozone content. We use the well water to replace evaporation loss and water lost by dogs splashing. The pond is about 750 gallons and has a pump and skimmer/waterfall setup that is supposed to be effective for 1000 gallons or more. In the last month or so the algae has been turning into brownish bubbly,a stringy blankets that float to the surface and I have needed to clean the system continuously to keep the filter from clogging. The snails have almost disappeared and some of the sheels I find are thin and have holes in them. I'm wondering if the ozone could have this kind of effect but it seems to be such a small amout for the volume in the pond. The mosquito fish and frogs seem unaffected and the pH tested at 7.4 but that was as high as my test kit went. Any help you could give me would be greately appreciated.

ANSWER: Ozone is actually good for ponds.  The only thing that seems to have changed is the work you had done on your well.  It's hard to put your finger on exactly what makes a particular species of algae thrive in a n environment.  What allows pond owners to handle many problems is an adaptive maintenance routine.  It seems you had everything under control up until the well work.  Try to alter your maintenance routine slightly in several variables, on at a time.  See what works and go with that, or keep tweaking your strategy until it seems right.  An additional option is to get a comprehensive water testing of the well water, look for an excess algae-fueling nutrients in the water.  Take steps to eliminate those nutrients from the water before introducing it to the pond.

Until then, you need to remove the brown algae, because it releases toxins into the water as it dies.  Try and wean yourself off the algaefix or do more frequent water changes to rid the water of excess algaefix.

---------- FOLLOW-UP ----------

QUESTION: Thanks for your quick reply. I haven't used algaefix in about 2 months since the algae was dying all by itself and all I had to do was scoop it out. What is the effective time span for algaefix? I thought it was relatively short since the instructions for use are on a weekly basis. Also, any thoughts about the snails? Thanks again for your help.

Answer
The snails probably starved.  There's not much that will kill snails without killing fish.  It is typically starvation, and you probably have plenty of them left in the depths.

Algaefix is effective immediately, but I'm sure your were asking the effective time span.  I unfortunately do not know this and was surprisingly unable to find this information online.  I would guess that it fully reacts within 4 hours.  Now, just because it is fully reacted doesn't mean all the harmful chemicals are gone.  This is why the bottle will usually recommend a water change some duration after treatment.  In fact, this amount of time listed on the bottle may be your answer.