Do Sludge Pellets Really Work?

We are commonly asked if “Sludge Pellets” really work.  As with many things, the answer typically is “It depends.”  Sludge Pellets, aka Muck Pellets, are a blend of bacteria and enzymes that work by breaking down organic material into smaller and smaller components.  Will they make sludge completely disappear?  Probably not.  Think about it this way, if you have a compost pile, will it completely disappear after it is broken down?  No, at best it will become a much smaller pile of compost.  Pond sludge is the same thing. Depending on its composition, the best you can expect is for the pond sludge to break down into a smaller accumulation of debris. How well the Sludge Pellets will break it down depends on a number of factors.

The first thing to consider is what the sludge is made of.  If it is a grainy sort of silt that accumulated from erosive runoff, then it probably is mainly inorganic material that will not break down well.  The only thing that will get this sort of sludge out of the pond is excavation of some kind, and Sludge Pellets will do little to no good.  However, if the sludge on the pond bottom accumulated from leaves, algae, weeds and other organic debris, then Sludge Pellets stand a good chance of working.   

Obviously, the more material that gets into the pond, the more sludge that can build up.  But there are other things that determine how bad the sludge becomes – the biggest factor being the amount of oxygen present in the water.  During the summer a warm layer develops on top and a cold layer on the bottom in your typical pond.  These layers normally will not mix again until late fall, and as a result the bottom layer runs out of oxygen because it is not exposed to the surface air.  If there is no oxygen in this lower layer of water, then any organic material that drops to the bottom tends to accumulate rather than break down, because most beneficial organisms are not present without oxygen.  However, if you introduce oxygen, then the beneficial organisms will follow, and the rate at which the material breaks down greatly increases.  Therefore, in most situations, properly designed pond aeration is more effective at preventing organic sedimentation than Sludge Pellets alone.  We tell our customers not to spend the money on Sludge Pellets unless they first aerate the pond.  However, if you do both together, you can have even better results.

Another way that aeration can help with sludge control is by warming the bottom layer of water.  Aeration works by sending the warm surface water to the bottom and the cold bottom water to the surface, thereby making water throughout the pond roughly equal temperature.  This is important because the colder the water is, the less active natural sludge reducing organisms are.  In fact, when water is below 55°F, very little decomposition occurs at all, and that’s why instructions for most Sludge Pellets say to apply when water is above that temperature.

So, what if you are unsure about the makeup of your pond sludge, or how well the pellets will work?  In that case, we recommend buying a 10 lb bucket, which can treat a ¼ acre for 5 months, and setting up a test.  Start by defining a 100’x100’ area, which is about ¼ acre, and measuring the sludge depths in several spots.  An easy way to do this is to take a long pole or pipe, put it down in the water until you just feel the beginning of the sludge, and then measure how far down it sinks before hitting a more solid bottom.  Record this information, do the treatments, and at the end of the season redo the measurements to see if you made any headway on the sludge, or at least held it in check.    

Finally, which Sludge Pellets are best, and which are the best value?  It is hard to say which are best because there is not much standardization within the industry.  You really need to judge this based on results.  Regarding the best value, you should compare how large of an area can be treated for how long, rather than how expensive a bucket of pellets is.  For instance, our 50 lb box will treat 1-1/4 acre for 5 months.  If you find a product that costs half as much, but will only treat 1 acre for 3 months, then it is not as good of a deal. 

In summary, if you would like to treat the sludge at the bottom of your pond, we recommend the following:

  • Make sure the sludge is made primarily of organic material, like leaves and algae
  • Install an aeration system if you do not have one already
  • If you are unsure how well Sludge Pellets will work, set up a test treatment with a 10 lb bucket
  • Treat with Sludge Pellets for a full season when the water temperature is 55°F and above
  • Check the depths of the sludge in your test area at the end of the season, and see if you made progress

One last thing to consider, when you are considering the effectiveness of the Sludge Pellets, you need to account for the new debris that continues to accumulate.  In most cases, if your sludge depth does not increase, or if you make slight headway, then the pellets are working!