Pond Boss Forums GENERAL QUESTIONS Water chemistry Does water quality change?

Do chemical qualities like alkilinity and PH change over time? I'm talking about from a practical standpoint.

Can I assume (dangerous I know) that it should be OK to send samples of my water to a testing lab, get the results and bet that they won't change unless I do something chemically to alter it?

If it can or does change, what other than my meddling can cause the change? What do I really need to watch for? How can I screw up a good deal?

Anyone?

Dave, Hang on. I've got a lot of experience in pH variability within a single water body over time. You'll find it really interesting.

Just got back from TX, killed a hybrid Ibex. Looks like it might be in top 5 ever with a bow, anyway. THe alkalinity will not change but I bet pH will. pH as you know has a diurnal fluctation so it depends on what time of day you take the sample and it might change in the sample bottle, unsure. The alk and hardness testing should reamin unchanged, good luck. I wish I had more time when in TX to visit some folks but speedy trip and y'll have an awesome state.

Congrats on the trophy Greg. Any pics?

pH and alkalinity can definitely change due to many conditions. Acid rain and the environmnet around your pond will impact the pH levels for sure. Adding aglime will increase the alkalinity and help buffer the pH. The challenge is that as your water source is refreshed through rain and runoff your pond is going to tend toward levels it was at before adding the aglime. We put 4 tons of aglime in our 1 1/2 acre pond last summer and it really balanced the pH nicely. Then we got a very rainy period and replaced hugh volumes of the water. I'm guessing we effectively replaced the whole ponds water supply several times over in less than 2 months time. Needless to say the pH went out of wack again even though our alkalinity levels stayed good. Before the winter freeze we were still acidic but somewhat improved. It takes some time to buffer the pH and I think we may be adding more aglime again this spring. Will have to wait and see as the spring melt again causes major refresh of our water.

Tuzz, You have a really great website.

Dave,

During the night plants undergo a process called cellular respiration. Because sunlight is unavailable for energy, plants will respire in order to obtain their energy from carbohydrates stored from previous photosythetic activity. During the process of cellular respiration carbon dioxide is given off. This carbon dioxide depresses pH, sometimes quite a bit. pH levels drop and drop throughout the night until sunlight is available to start photosynthesis. During the day pH levels will increase. This pH cycle can change pH values by as much as two full points during the day. This is important because ponds that are artificially fed can have higher levels of ammonia. Ammonia comes in two primary forms-- ionized and unionized. When water becomes more acidic (lower pH) there are more hydrogen ions available to bind with NH3 forming NH4+ which is the ionized form. This is less dangerous to fish. When water becomes more basic (higher pH), fewer hydrogen ions are available and NH4+ loses hydrogen ions to the water and reverts back to NH3 which is the unionized for of ammonia. This is extremely toxic to fish in high enough concentrations. Bottom line is that high pH creates an environment with more dangerous unionized ammonia and fish can stress or die.

An accurate assessment of your pond's pH would involve testing at various times of the day, in particular at 1 hr. before sunrise and late afternoon to establish how wide your pH range is.

In addition to Dr. Condello's science report above, pH will change more easily or quickly when-

1. Water has less or lower alkalinity

2. Water has more plants present, either phytoplankton or rooted plants.

What Dr. Condello did not mention is that when carbon dioxide is released into the water it forms carbonic acid which lowers the pH esp during the night. During the day the carbonic acid breaks down into bicarbonate.

Carbon dioxide is also always produced 24/7 from bacterial decompositon and animal respiration.

pH is less likely to change when your water is more buffered with limestone either natural or added by you. Ponds in some regions contain naturally hard water (lots of lime). My pond water alkalinity is naturally always around 96-100 ppm (mg/L). Above 20-30 is needed for a good plankton bloom.

Are you giving me a hard time, Bill?? :p

Bruce,

I think he is! He does that to me too! :p

Thanks all. It appears that I can probably sleep nights unless my environment gets altered by acid rain, large amounts of plants with a tenuous life, etc. Or possibly a large rainfall after a long drought.

Not a lot I can do about acid rain and we don't seem to have much problem with it in North Central Texas.

Plants can pose a threat but grass carp have taken care of the pondweed. They aren't doing much about the coontail.

Large rainfall after a drought is always a potential problem here, especially the drought. For that reason, I quit fertilizing 5 years ago and haven't had a DO crash since. It is not unusual to have 20 to 25% less water volume by the end of the summer.

I wasn't consciously thinking about it when I posed the question but I'm thinking about experimenting with tilapia. The potential biomass problems combined with the ever present lack of rainfall worry me. A couple of years ago, I put a pound of fatheads, 100 bluegills and 25 channel cats in a small 1/8 acre pond. They spawned predictably and I seined heavily twice and added the minnows and BG to a neighbors new pond that I now own. Then I quit because I couldn't get anyone to help with the seine. They kept spawning and polluted the water. It turned into a nasty looking green mess and everything died. That leaves me losing sleep about tilapia in my 2 one acre ponds. On one hand, it could put me over the top in bass growth, take pressure off bluegill for a year and go from a ho hum water hole to a really good one. On the other hand, I'm remembering the polluted mess that Mama Nature and I created with the forage pond. The greatest tilapia and resulting BG biomass should come about the time I have the lowest water level.

Larry Hartley (Meadowlark) has done great with tilapia but he is in East Texas and the difference in East Texas and West Texas is a 4 letter word R-A-I-N.

Hey, one thought. As filter feeders, would tilapia help clean their own water?

Bruce and Cecil - I plead for redemption.
Your chemistry explanation was very accurate; lots of info packed into that short post. It once again reminded me of chemistry class. It may appear I was giving you a hard time but it was a subtle way of saying the ionized, unionized ammonia ammonium, pH, NH3 carbon dioxide, NH4+ hydrogen losses and gains had me a little dizzy. Getting me dizzy is not too hard for someone to do. I was thinking about the average pondowner & fisherman and how they would perceive your description -explanation . However, it is a complex topic to simplify with easy to understand words. Job security for chemists I suppose.

Bill, I think we have to have both on this forum. We have to have the very technical and the simple explainations. We do this with aeration, drain sizes and lots of other issues.

My guess is that pond management started out as "get rid of the bullheads and green sunfish and put in bluegills and LMB". We are expanding way beyond BG and LMB in our thinking. Along the way, many people are moving beyond "just add lime" to understanding why we add lime. I think that in every answer we need both the simple and technical answers.

Norm, you got me I'm the one with the simple answers and leave the complex ones to BC and others. They explain it better than I can and I run out of time when I try to get too complex. I promise I can explain much better by speaking than writing.

Bruce, I thought you were trying to emulate Bill Cody. Just like Bill, I had to read your post 3 times but it was absolutely worth it. Had you brought it down to the stupid level where I live, it would have taken several pages.

Now you guys know why my posts are so long. The secret is out now. Sooner or later the truth comes out. Dave and I live on the same floor or level; the "simple or stupid floor"; that is probably why we are not dentists or rocket scientists!

I read all this with great intrest. Not that I pretend I will retain it all but I am very greatful you guys post these explanations. You answer questions I didn't know I had until you presented them!
Greg, Bill, Bruce, Dave & others I have great apreciation for your knowledge & willingness to share.

I have to admit though Bill & now Bruce's post do sometimes take more than one reading to comprehend!
And Bill, you described my sensation exactly when you said Bruce's post made you dizzy! That's exactly how I felt!

Dave,

Best investment you can make for water quality is an aeration system. I would put it in in the Spring and begin to run it a little at a time until you work up to running it 24 hours a day seven days a week. You need to work up to 24X7 or you can cause a big problem. When we put ours in last June the smell coming up from the bottom was nasty. This from basically a brand new pond. You could poison your fish with that bad water from the bottom if you do it too fast. The smell will go away as you run it and your Disolved Oxygen will increase nicely. Another benefit will be that if you use the pond to swim you won't get the "slimy's" that you can sometimes get on your skin from anerobic bacteria.

Thanks for the comments on the web site. A hobby of mine. Designed it for my friend Scott from Catskill Pond who designed and built the pond for me. Will be doing an update soon if I can get him to move to a real hosting site. It's hard to do much much on a site that only gives me 10 meg. of space to use.