Pond Boss Forums GENERAL QUESTIONS Water chemistry Well Water?

I am a new subscriber to PB and new to the PB Message Board!

I have a new client with a 15 ac. lake that was used for irrigation by putting well water continuously (600 gal/min) into and then pumped out for almost five months. Approximately 18 months ago it was stocked heavily with bream and minnows and was assumed to be ready to stock with largemouth bass. This is why I was invited in, because the lake owner said very few fish are visible and no dead fish were ever obsereved, so the hatchery wanted me to shocked it. I found very few minows and even fewer bream. The pH is just above 10, Alkalinity was near 50 and hardness just above 100. No shoreline vegetation present, but some Southern Naiad is covering the bottom, but is only a foot or so off the bottom, not growing like I would anticipate, unless the well water is slowing its growth? The water is crystal clear. Most of the stocked fish have perished due to the amounts of well water applied to the lake. The DO is now around 6 at dawn. My question is - will the pH gradually come down on its own, or is there an application of something that should be applied to help it get back within a desirable range? I have dealt with many lakes needing the pH raised, but never one needing it lowered? The landowner has agreed to remove the lake from the farm irrigation system, so that too much well water will not be a problem in the future, but for now what are your suggestions?

Thank you in advanced for any assistance.

Welcome S Brown. Hope you're here for the long run.

Have you considered adding alumnum sulfate? I currently have three ponds where the pH raises to over 10 every afternoon. Here's a link to a thread that discusses alum application, how to do it, and what effect it may have on your lake or pond.

http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Main=5386&Number=49373#Post49373


I'm not necessarily recommending this---just throwing it out there for discussion.

By the way, my ponds are entirely filled with well water. My fish thrive 99% of the time, but sometimes there are issues with pH that arise from the high alkalinity, conductivity and pH that come along with the groundwater.

Bruce

Welcome to Pondboss S Brown. I am from Allen too.

Something doesn't sound right. At a pH of 10, hardness solubility should not be 100 ppm as CaCO3; certainly not as ion. Alkalinity could be this low, but would likely be higher unless you are pulling from a lime deposit sand. Hardness at twice the alkalinity indicates calcium chloride or sulfate, or magnesium salts of the same. High levels of non-carbonate hardness would typically be the case at pH ranges nearing neutral, not above 9.0.

The pH at this level is detrimental to fish growth and health. Natural waters do not stay at this level unless they receive additions of lime, caustic soda, or soda ash. Lime and soda ash are naturally found soil deposits in some areas. I have not heard of that being the case around your area of Texas. The only area in Texas I am familiar with that has wel water that high in is water is near College Station, where well water runs 9.5 pH, but low hardness from the natural soda deposits. This water is extremely soft (low in hardness)from the high pH and high sodium content (solubility of hardness salts at 10 pH and ambient conditions is less than 60 ppm due to retrograde solubility).
I would check the pH out of the well. If it is this high, you will need to add sulfur salts such as ferric sulfate to lower pH with out lowering alkalinity. Once the pH is lowered, CO2 solubility will increase, and alkalinity and hardness levels will stabilize.

Very informative post, M.

Great post Mike !! I agree something is not right with those facts and results.

The lake is not in Texas, but north of Tifton, Georgia. The wells on the farm are excessively deep and many feet into limestone, the owners say. The owners are replumbing the farm irrigation system to bypass this lake for agriculture practices, but manage it for a quality fishery only. This lake will no longer recieve well water unless it is an absolute emergency. They are putting in desirable aquatic vegetation and an aeration system this winter.

I appreciate all the comments and assistance. It looks like this board will be a great wealth of information. Since I have clients from Texas to Florida, I'll state the location of the property in future posts. Thanks again!