Pond Boss Forums GENERAL QUESTIONS Water chemistry NO OXYGEN!!!

New pond built where old beaver pond existed, in swampy bottom. Three months after pond filled (app. 7 acres), introduced bluegill, which immediately died. Today I confirmed our suspicion, which is low oxygen. The D.O. measured anywhere from 3 at the surface to .7 four feet below the surface. PH is 4+. Our theory is that there is an abundance of decaying material which is robbing the water of oxygen. If we're right, the question is, how long will it likely take for the oxygen level to rise? Pond has great inflow of water, steady outflow through 60" pipe over flashboard riser.
Note that we also tested the 20-acre pond five hundred yards downstream with the same water source and found the PH is identical but D.O. is 10 at the surface, 8.5 four feet down. First post for me. Thanks!

Welcome, Dawgponder. Your post will get appropriate attention, I'm sure, but it would be really helpful to know what the pH is throughout a typical day. Ponds with high organic load undergo significant daily shifts in pH through plant photosynthesis and respiration, and knowing a pH of "4" could mean that it varies from 4 to 6, or it could mean that it varies from 4 to 3. That would mean that there may be another significant factor in fish survival, or lack thereof.

Again, welcome.

Welcome as well Dawgponder. Bruce made a great comment about the pH. As the carbon dioxide levels change in the pond, so too will the pH. At levels of 3-4 or 4-5, these are some very low levels for most fish.

If possible, this weekend, spend the day taking samples every hour and then graph it. Start about 7 and end at 11 pm.

If aeration were a possiblity, the more information you can gather will aid in properly sizing the system. One important item would be the BOD or Biochemical Oxygen Demand. This test can be done by a local lab like TestAmerica. Check with your local wastewater plant to see who they use to test their water.

BOD will allow us to size a system to meet the demand of the lake. This will take in all of the dynamics of oxygen consumption and it takes 5-days to run this test properly.

I'm sure you will have other professionals chime in on this one especially with the title you used!

I hope that all of us will be able to provide enough information to allow you to make an informed decision on the right path and plan of action for your pond.

Happy pondering,

Bruce and Cary -

Thanks for the info. Our next step is testing BOD, which I'd never heard of before today. One curious thing to me is that the larger pond downstream (with same low PH)has "great" fish, meaning that we regularly catch very healthy bass in there. There have been very few bream caught in that pond, which makes me wonder if they're even more vulnerable to low PH (or maybe it's just out of balance in that regard).

Dawg,

I'm not into the stocking rates as much as the others, but running on the shocker boat with Greg Grimes, I witness this particular 20-acre lake that had very low rates of bream, so much so that the bass were eating their own.

I would say it is more a stocking rate than the pH affecting the number of bream.

Guys I would suggest that alkalinity is a better measure of the acid/base relationship in a pond and thus the water's ability to buffer ph swings and O2 loss. Could you take DO readings over a day long period in both ponds?

I wonder what the watershed for these ponds is like. With high inflow and outflow I doubt that the major factor is decaying material in the new upper pond. If it is a new pond - how was it made? If the bottom was constructed then there should be very little bottom material to decay unless there is very large weed/plankton problem (doubtful with low alkalinity/ph). If the construction uncovered silt and debris with high H2S content and that is exposed to the water it would effect O2 levels and ph/alkalinity. If I recall H2S + O2 makes sulfuric acid.

The fact that the upper most oxygenated water is leaving the upper pond over the riser could be a factor as that would tend to deplete the O2 in the upper pond and increase it in the lower pond. I will further note that many swamps have acid water that is still very productive and with excellent populations of BG and other fishes which are less tolerant of low DOs.

Was the upper pond limed when made and were any soil tests done?

http://aquanic.org/publicat/state/il-in/as-503.htm

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=22;t=000038;p=1#000000 archives "fish kill causes"

One of my first thoughts centered on the organic matter question. " NEW POND where old beaver pond existed, in swampy bottom" would lead me to agree with Eric's post. Decaying organic matter shouldn't be a factor.

Dawgponder, can you explain a bit more about the inflow of water? If this source is straight ground/spring water, O2 levels may be low to begin with. Although the same source feeds a 20 acre pond downstream, would a 500 yard run be enough to increase the O2 levels to the numbers stated above?

russ.......yes, i believe so.

More thoughts and answers to a few questions:
-Pond was constructed by removing beaver pond and building earth dam, which raised level app. three feet above beaver pond level and greatly increased surface area of pond. Before we did this, there were plentiful redbreasts in beaver pond and creek (I assume they are now gone unless they've taken to land for air!).
-Soil in surrounding area is very sandy.
-Russ, great question about how water is increasing in DO that short distance downstream; yes, inflow is all spring/creek.
-Not asked, but there are three other healthy ponds within four miles upstream, all ten acres or more.
-No liming done yet.
-There has been a strong sulfur smell at the spillway, which is almost gone now, as is the "foam" on the backside of the spillway.
-If it matters, pond is relatively shallow, averaging five feet in most of the middle.

IF decay turns out to be the issue, any thoughts on how long something like that might take to clear up (months? years?)???

It's not unusual for beaver ponds to silt up. They catch and contain all of the waste that comes downstream. Typically, the silt laden pond becomes a marsh and the dam blows out. The beaver then goes elsewhere.

I know of no reason that it would clear up in a "reasonable" amount of time. As usual, I could be wrong.

Dawgponder,

Based on the new information you provided, I would have to amend my first post concerning my comment on decaying matter.

Like DD1 has stated, your pond is doing what ponds do naturally. They act as a catch basin with the sediments accumulating to the point where the pond is no longer a pond. I also concur with Dave's statement that if you do nothing, the problem will not clear up in time.

Cary mentioned aeration. The most dramatic example of the benefits of aeration, pertaining to muck reduction, is posted here in this link. Look for Sue Cruz's post. Not to say that aeration will solve all your problems but given the option I think most, if not all, PB members would agree that it would certainly help in your situation.

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=15;t=000029#000001

As always, PB experts please correct any misguided information I may have posted. Thanks.

Aeration should help and is a good idea but don't expect it to cure the underlying problem. I don't think it will solve an acid water problem (sulfur smell) that comes from the surrounding basin and dirt nor will it solve the fact that probably the best water flows out of the top 3 feet of the pond over the riser. In fact over the very short term stirring up the bad bottom material could make the water worse. I suspect that is what happened - the bottom debris was stirred up or is decomposition rate was accelerated by construction and that plus the loss of a lot of surface aerated water over the riser concentrated the acid water/nutrients and resulting O2 usage. Result a fish kill.

For my 2 cents - get the dirt and inflow water tested and take steps to fix that. It may require a track hoe, adjustments to the riser system and some lime. Then some aeration can really help maintain the water quality and buffer against problems. Aerating the muck/debris out of a 7 acre pond/bog is no small job.

Lots of good comments and I can add little.I agree alkalinity and multiple PH tests of inlet water and soils are a good idea. Aeration as ewest suggests will do little to acid water, If your sulfur is present due to an anaerobic condition (likely is)then aeration will help that. Muck levels in a 7 acre pond that was swampy can be problematic to reduce. Not sure if "new" pond rennovation removed a lot of the "old" pond condition or not.Figure at least a full turn of the entire water column per day to even start to get a handle on this pond.This pond once aerated "should " get worse before it gets better but often is just part of the normal procedure for changing the condition. This pond also sounds like it would benefit from retrofitting a bottom draw outlet tube into the 60 inch existing outlet.Perhaps a 24 inch tube inside the 60 inch that would trickle off of the bottom where you would still have the extra capacity of the 60 inch for ultra fast flow when needed. Always a downside to fast in and outlet water without aeration is that the naturally aerated water is sucked off the top.It does not take a lot of aeration to keep fish alive in a medium stocked 7 acre pond but it can take a different system to meet a higher goal of eliminating the entire anaerobic condition on the entire pond bottom.