How To Get The Most Out Of Pond Bacteria

As an Amazon Associate we earn from qualifying purchases.

This is a rather lengthy article that talks in depth about how to get the best results when using a beneficial bacteria product in your pond or water garden. It’s worth taking the time to read but if you want a condensed version of the main points please watch the video below.

Of all the possible remedies that exist for restoring a pond to a better condition, there are few if any that have the power and benefits that beneficial bacteria can offer. These helpful little microbes that have existed in ponds, well, since the beginning of time or shortly thereafter, are little cleaning powerhouses.

The term “cleaning” is fairly accurate because beneficial bacteria help to reduce or clear up a number of things. Ammonia, which is deadly to fish, is broken down into harmless substances by bacteria. So are nitrites, which have their own degree of toxicity. Then there’s the nitrates and phosphates. These two types of nutrients are prime feeders of algae, and while they’re not necessarily bad, if they are high in number, your chance of having an algae bloom is pretty good.

pond bacteriaThe fact that these natural nutritional sources help algae grow, are very important for anyone who’s looking to try and limit algae growth naturally, because if you limit them, reduce them, or simply stop them from being absorbed by algae, often times the pond will clear up.

Although this approach is a more indirect route (and doesn’t treat the algae at all), compared to chemical algaecides, it can provide a safer, more eco-friendly way, to deal with an algae bloom. Chemicals usually will work faster, but if they’re applied incorrectly, fish can be lost quickly, and in the end, dead algae can accumulate at the bottom of the pond and actually feed more algae growth. For our purposes, chemicals can easily take a pond in the wrong direction when your goal is complete restoration.

It’s estimated that we suggest the use of pond bacteria in about 85 to 90 percent of the pond’s we work with. It is our favored place to try to improve things. This is not to say it works perfectly in every pond (hint: nothing works 100% of the time – even chemicals) but it provides the best opportunity to safely improve many conditions. Usually after a month or two (and sometimes within a matter of a few weeks), you’ll see some improvements, and in some ponds it may take a bit longer, but after a few months of treatments, you’ll know fairly well whether bacteria will help with algae problems.

When it works well, the process seems almost miraculous because algae will simply regress or disappear. When this happens you obviously know that you got a very good response with the bacteria. A common question then comes up. “Will I have to treat with this stuff forever?” Our answer to this is…not usually. The only caveat to this is if the nutrient influences are constant, then it’s a matter of routinely offsetting them. If they can be reduced and managed, the pond will stay clean with less supplementation.

So, when we work with a pond, our intent is not to rely on bacteria supplementation forever. In many ponds this is simply not necessary. And while bacteria will always help in some way, it’s important to remember that for our purposes, we want to see a change in appearance of the pond, and for that to happen, the bacterial response needs to be optimized to get the best results.

Treating A Pond With Beneficial Bacteria

So here’s our general approach to naturally treating, and evaluating, an algae laden pond. Taking these things in to consideration will help anyone achieve the best results with a beneficial bacteria supplementation.

Rule #1 – Get The Dosage Correct

First you absolutely must get the dosage correct and the baseline for that is to use the gallon capacity (or acre feet for large ponds) and use this volume as your minimum dosage requirement. From there you need to look at what could be called “nutrient influences”. Does the pond have a fair number of fish? Does it get exposed to a lot of sunlight? Is there a lot of muck at the bottom or decaying material? Could the source water or runoff into the pond be high in nutrients? (think golf course, fertilized yards, livestock operations, or farm ground for example). If this is high in some way, increase the amount required up to double the amount. So for example a 1,000 gallon pond might require up to a 2,000 gallon dose. A 1/2 acre pond might require up to a 1 acre dosage. Its very possible to do this safely with bacteria because to some degree it’s very self regulating. It’s difficult to use too much and hurt anything, but using to little will likely produce poor results. Be sure to use a pond calculator if you don’t know how to figure your gallons size and if you must, overestimate the size a little rather than assuming it’s smaller.

Rule #2 – Use The Bacteria Long Enough

Remember, bacteria is not a chemical and it doesn’t work like one. This is favorable for most ponds because algaecides can kill algae quickly but in doing so, it can pull oxygen from the water very fast and harm fish. With a microbial approach, changes normally happen quite gradually. Many people, unfortunately, can get impatient and desire a quicker fix so they abandon the routine too soon, or simply give up on it. There is an appropriate time to stop adding bacteria if you’re not seeing changes, but it’s important not to stop too soon.

It’s very common and exciting to see changes in the pond in the first 30 days of treatment but it’s not out of the question that it may take longer to improve things. We suggest always giving a bacteria program at least 60 days to see if it will begin to turn the pond around.

If we see improvements, we continue on until the 60 days are up, and then we would normally stop adding bacteria and see if the pond will stay pretty clean. If it does, then we simply wait and see how long it will stay clear (pond aeration helps with this). Some ponds will go quite a long time without needing more supplementation. Others may need continuing treatments. If algae comes back after the break in treatments, you can always add more bacteria and the clearing response is normally quicker in the follow up. We would treat another few months and then stop again and evaluate the response. We do this for as long as necessary until we can get some extended times between treatments. Over time, you can usually expect this duration to improve.

Rule #3 – Don’t Suffocate The Good Guys

Although the topic of pond aeration could probably fall under the title of “pond accessories” the reality is when it comes to bacterial work, oxygen at the bottom of the pond is absolutely critical. Without good levels of dissolved oxygen in the pond, the microbes (which are aerobic) will simply not have the gusto to perform at their best.

I have often likened it to running a marathon. I don’t run much you see, but I would wager that if you put a sealed plastic bag over the head of the best long distance runner in the world, and allowed me to race head to head…I may not finish the race (after all it’s 26 miles for gosh sakes) but I’d surely beat this great athlete. Without access to oxygen he won’t get very far down the road at all, and beneficial pond bacteria is the same way.

Fountains, since they sit at the surface, will help a little bit. They may work better in shallow waters and provide some assistance. However in ponds that are deeper than six to eight feet, the oxygen levels will often drop as you go farther down, and unfortunately it’s at the bottom where a lot of the bacterial work is done. The only way to truly test your oxygen content deep in the pond is through a DO meter with a probe on it. Without that, one can only assume that there’s enough dissolved oxygen to go around, and unfortunately, assumptions are known to be wrong.

So go insure the very best results with beneficial bacteria, it should be noted that all of them work best when sub-surface, bottom based aeration is present. This provides good oxygen content in the water, and it allows for good circulation too, which guards against stagnation. Plus it’s very good for fish stock too.

In ponds with good aeration we often see a faster and better response with bacteria. Often you can get more bang for the buck out of it and extend the time between repeated or follow up treatments. Without aeration, we sometimes see a sluggish response where the treatment time may need to be extended or a higher dose of bacteria is needed to stimulate a response.

Rule #4 – Don’t Give Up Too Soon (Evaluate and Adjust if Necessary)

If we don’t see improvements in the pond in the first several months, we may do some troubleshooting to try and figure out why things aren’t changing. Some of the common questions we might ask are…”Is there ample aeration in the pond? (and by the way, don’t assume just because you have a waterfall, or incoming stream from fresh water that you have good aeration) What is the water chemistry such as the pH, alkalinity, or hardness? What are the nutrient sources? How many fish are in a small pond, what kind are they, and how large are they? What type of filtration is being used?”, just to name a few.

Ultimately we want to try and figure out why the bacterial response might be sluggish, hindered, or why it’s not able to balace the nutrients out. If most of these numbers and variables look good, or we can’t narrow any one thing down to being a problem, we might suggest the pond owner try another formula of bacteria. It may be a brand we use, or someone else’s. In truth, most of the bacteria formulas on the market are intended to work in a similar way as we described above. Yet the recipes, and concentrations of bacteria do differ somewhat and it’s not been out of the question to have folks try one type of bacteria, not find it helpful, then switch to something else, and get better results. One blend may simply fit the conditions in a pond better than another one and it’s often worth giving another formula a bit of time to work. We would follow the same routine as above and evaluate the product for about 60 days.

So the moral of this story is to not give up too soon on the idea that bacteria can be helpful. In truth, it’s always helpful. The question is, will it perform well enough to clean the pond up the way you want it to. We prefer to provide every opportunity to move the pond in a better direction using bacteria, before we decide to limit it’s use and move on to other things. We may even add other things to the mix to help it along if we have to because, simply put, it alone may not always be enough to get the job done.

One of the positive parts of using a bacterial approach is that it can, and often does play well with other pond treatments and additions. Barring copper containing algaecides and many herbicides, microbes can be used along with a variety of other products. And often the response that you’ll get with bacteria will be greater, or more effective when you combine it with some of these things. We call this “stacking” and we’ll talk about it more in next week’s article. Along with that, we’ll discuss when it might be time to move on to something like a chemical option if it fits the need or you’ve come to a point where not much else seems to help.

, pregnancy, heart disease). Pharmaceutical edtabs companies are frequently called upon in legal actions to address alleged violations of the law.

Amazon and the Amazon logo are trademarks of, Inc, or its affiliates.

8 thoughts on “How To Get The Most Out Of Pond Bacteria”

  1. I have a two year old pond that I stocked with 1200 bream and 160 bass. The bream were stocked 2/15/17 and the bass about 6 months later. The pond is ~1/3 acre. It is 7-8 feet deep on one end and 2-4 feet deep on the other end. Last year I had a good bit of algae build up that my wife and I would have to skim off using several lengths of pvc pipe with ropes tied to the ends. We skimmed over the concrete wier I had built at the end of the pond. I installed two aerators about 4 months ago. Should I put benificial bacteria in the pond now or should I wait until the weather warms up some. I live in Zachary, Louisiana. Will too much of the bacteria harm my fish? If the pond still has algae after my first 60 day treatment should the second dosage be more than the first dosage? Thanks for any help you can provide.

  2. Hi Ricky…since you have an aerator going you’re in good shape to add some microbes now. I would look at our 1/2 acre biosphere pro on our website…this is pre-dosed to treat any pond from a 1/4 acre up to a 1/2 acre in size. Use one of these per month for two months back to back, prior to going into the algae season. You could start now even if the water is cold. The reason I suggest these spheres is they use an all season blend. Many bacteria products are using only warm water microbes that start working above 55 to 60 degrees. And that’s fine…unless you try to use them in cooler waters.

    So I try this and evaluate in the 60 day period…after that, if you feel you’ve seen some improvement, I may tinker with the dose for a time. I may also try a different type of microbial…some work better than others in certain situations so it’s worth doing that before moving onto something else entirely.

    As far as safety…microbials won’t hurt the fish at all. I do think it’s always wise to have aeration going for their benefit so you have that covered too.

    Hope this helps for you.

  3. Mark, one more question. Should I place the biospheres near the aerator or somewhere in the middle of the pond?

  4. Hi Ricky,

    In terms of proximity to the aerator it won’t really matter that much. The aerator, when it’s properly sized, will turn the pond water over, or circulate it completely once per day in most cases so that alone will distribute the microbials very well.

    All the best,

  5. Mark, I also have another issue with my pond. I have what I think is Watershield (after looking at some photos online) growing around the edges of the pond. Had some there last year but it is spreading more this year. It is about 2-4″ around and stands up out of the water 6-8″ with roots in in ground. I would like to spray them before they take over but need advise on what to use. Certainly don’t want to harm my fish population. Let me know what chemical I need to purchase please. Thanks, Ricky Braud

  6. Hi Ricky,

    Usually when weeds come along my best advice is to visit a site called Aqua Plant from Texas A&M. There you can confirm the ID of the plant but as well, under the management options tab you’ll find the latest treatments specifically targeted for the plant…these could range from suggestions with physical removal, grass carp, or some kind of chemical. Here’s the link for it.

    I think you’ll find a good solution there.

    All the best,

Comments are closed.