What type of pump to use for spraying organic compost tea???

Discussion in 'Organic Lawn Care' started by Rick13, Jan 12, 2013.

  1. Rick13

    Rick13 LawnSite Senior Member
    Messages: 408

    There are two types of pumps: Diaphragm and Centrifugal.

    I've done a few searches in Lawnsite, Google, Spraying Companies (selling their own equipment), & Yahoo Compost Forum. And after reading these searches... everyone has a different idea which one is better at protecting microorganisms.

    Some like diaphragm pump, but don't like the pressure and it may get plugged up from the compost tea.

    Others like centrifugal pump because they pass everything through, but their impellers can hurt microorganism...thus hurting your compost tea.

    So who's using what type of pump for spraying compost tea in the field?

    And has anyone sent any of the compost tea to get checked after they've ran it though their spraying equipment? Is the microorganism still good?


  2. Rick13

    Rick13 LawnSite Senior Member
    Messages: 408

    Diaphragm Pump Sellers:
    Compostwerks (50, 100, & 200 gallon) Sprayers
    NorthStar (55, 100, & 200 gallon) Skid Sprayers
    Gregson-Clark V-Series (50, 100, 200, & 300 gallon) Skid Sprayers

    Centrifugal Pump Sellers:
    Rittenhouse (240 gallon) Skid Mount Turf Sprayer
    Rittenhouse (100 gallon) Gas Lawn/Water Spray Unit

    Rittenhouse also includes in their website under Compost Tea the following: "Because Compost Tea consists of solid particles, injectors are not recommended. Suctions Filters should be removed for Compost Tea applications".

    Compostwerks uses a compost tea transfer pump that's centrifugal pump, but their sprayers are diaphragm?

    Turbo Turf Compost Tea Sprayer has the following on their website: "If you make a decision to use a conventional lawn sprayer for Compost Tea never use one with a roller pump. A diaphragm pump unit is acceptable but try to run as low a pressure as you can which means you will need to bypass more material which some feel is not desirable but you can use a set up with a diaphragm pump. A centrifugal pump is the best choice".

    So these are just a few of the companies out there, so which is the best? Any ideas???

    I'm wanting a spraying unit that I can keep my microorganisms alive while I'm driving (so some type of aeration/air is needed to keep material alive). A unit that has a good gallons per minute (5 to 8 gallons), 300 feet of hose, electric hose reel, in 100 to 200 gallons.

    Any good ideas???? And if you have any prices ....that would be even better!!!
  3. Hi Rick, sorry for the long delay in relpying.

    My experince has shown that sprayers designed with diaphragm pumps do the least harm to microbiology in compost teas. This is through oberservations using direct microscopy.

    In theory, centrifugal pumps do the least harm...this is provided the liquid is going through the pump a very limited number of times. In the real world, we know this is NOT the case when using a sprayer. Sprayers run until the job is done or we're out of compost tea.

    The problem with centrifugal pumps is the impeller. As it spins, it can 'slice and dice' the biology. I believe this happens to a much lesser extent with diaphragm pumps within the valve system. I like the fact that (for example) the UDOR Kappa 43/GR has a GPM of 12.5...we can get reasonable volume of liquid out with a reduced RPM at less than 150 PSI. Reduced RPM's mean less opening and closing of the valves. I believe this is the reason we're seeing better results with diaphragm pumps.

    With any sprayer, my suggestion is to leave the pump off until it's time to spray.

    It makes me a little nuts that 'compost tea sprayers' are being marketed with fundumantal design flaws by people that have never sprayed compost tea. Please, let's have BIG strainers that are properly sized, accessible plumbing for cleaning...and how about aeration systems that work without the pump being on all day. There's several other design details that all add up to better results....and results are what we're being paid for.

    I hope this helps Rick.


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