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  1. #1

    Drum filter flow rates

    On the specs for drum filters, maximum flow rates are given. Are these effected much by other factors like biofilm dirt etc? As I'm presuming the numbers are based off brand new clean units.



    I'm looking at one with a maximum flow of 35000l, what would be the realistic expectation of flow? Also is it correct that you want a drum that is using most of its potential.



  2. #2
    Thereís a number of factors to consider Iíd suggest before deciding on drum size.

    Pond volume
    Turnover rate required
    Number and size of bottom drains/skimmers
    Pump fed or gravity fed
    Do you want any capacity ďjust in caseĒ?
    Thereís probably a couple more


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  4. #3
    Extreme Koi Member Rank = Nanasai blue harbour's Avatar
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    Yes muck build up on the drum screen will effect max flow rates, but there easy to clean with Brick acid when necessary.

    Iíd personally make you sure you have a drum that is more than capable of what you require in terms of how much you want to put through it flow wise, and also how many inputs/outputs you require.

    You ideally want to be putting all your water through your drum from every output/input you have!


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  6. #4
    Quote Originally Posted by bigcarpchaser View Post
    Thereís a number of factors to consider Iíd suggest before deciding on drum size.

    Pond volume
    Turnover rate required
    Number and size of bottom drains/skimmers
    Pump fed or gravity fed
    Do you want any capacity ďjust in caseĒ?
    Thereís probably a couple more


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    Pond is 34000ish litres.

    Currently running a hailea 12000 and an auga 30000 at 57%. I'm guessing realistically the flow over the shower is about 20000. My plan is to change the hailea for another auga and flow between 25000/30000 over the shower.


    Gravity fed.

    2 bottom drain

    Skimmer is on its own line.


    I'm not certain if I would need more capacity, water is fine now but I'm just considering the drum option for ease of maintenance and the lack of worry about filters not been cleaned when away.

    My concern is that if I go for a 35000 will it reliably flow 30000.

  7. #5
    Quote Originally Posted by blue harbour View Post
    Yes muck build up on the drum screen will effect max flow rates, but there easy to clean with Brick acid when necessary.

    How do you do this ie clean the filter screens with Brick Acid? Apologises for my ignorance, but I haven't heard of this technique

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  9. #6
    Hhmmm...isnít the rule of thumb that a 4Ē bottom drain can flow around 20k litres/hr at a push?
    Iíd be tempted if it were me to chuck both drains and the skimmer through a 55.
    I have a 35 Aquasource on mine with 1 BD, 1 skimmer, 2 Auga 20k and when I hoofed them both right up it was fine.
    Your pond is more like Felines I think and sheís running a big combi so Iíd possibly wait to see if she has any input to make Drum filter flow rates


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  11. #7
    Quote Originally Posted by bigcarpchaser View Post
    Hhmmm...isn’t the rule of thumb that a 4” bottom drain can flow around 20k litres/hr at a push?
    I’d be tempted if it were me to chuck both drains and the skimmer through a 55.
    I have a 35 Aquasource on mine with 1 BD, 1 skimmer, 2 Auga 20k and when I hoofed them both right up it was fine.
    Your pond is more like Felines I think and she’s running a big combi so I’d possibly wait to see if she has any input to make Drum filter flow rates


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    Do you have a shower on your pond? What flow would you estimate you are putting through the drum when both pumps are maxed out?

    Do you also have a uv in the drum, if so what size fits?
    Last edited by kikokuryu John; 21-05-2019 at 03:54 PM.

  12. #8
    I have a shower however itís not a ďnormalĒ one as such as itís designed to hold my own ceramic media.
    Thereís very little in the way of head or pipe bends so at a conservative guess Iíd say 15k litres per hour
    I have an amalgam uv under the drum. It wonít impede flow with any significance.


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  13. #9
    Quote Originally Posted by bigcarpchaser View Post
    I have a shower however itís not a ďnormalĒ one as such as itís designed to hold my own ceramic media.
    Thereís very little in the way of head or pipe bends so at a conservative guess Iíd say 15k litres per hour
    I have an amalgam uv under the drum. It wonít impede flow with any significance.


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    Sorry, misread your post...probably between 25 and 30k l/h


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  14. #10
    Quote Originally Posted by bigcarpchaser View Post
    Sorry, misread your post...probably between 25 and 30k l/h


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    It sounds like the 35000 will be fine for what I need. I can up the flow from what It currently is, take more crap out and less maintenance. Win win.

    What size uv do you have in the drum, is the size of the bulb an issue for fitting? I was thinking 2 bulbs so most of the drum is covered by uv light.

  15. #11
    Iíll have to check as I honestly canít remember. Will let you know.
    Iíve not looked inside while the drum is on for obvious safety reasons but Iím not sure youíd need 2. The amalgam lights are also a bit on the pricey side.
    I will have a look tomorrow



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  16. #12
    40w Drum filter flow rates


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  17. #13
    Quote Originally Posted by bigcarpchaser View Post
    40w Drum filter flow rates


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    Is enough space available for a larger/longer bulb?

  18. #14
    Extreme Koi Member Rank = Nanasai blue harbour's Avatar
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    Quote Originally Posted by Treadstone View Post
    How do you do this ie clean the filter screens with Brick Acid? Apologises for my ignorance, but I haven't heard of this technique
    When mine was done it was basically done by getting a smallíish paintbrush (say a 1-1.5Ē Jobbie) and the acid was poured into a small cup so you could dip the brush in it easily and then the acid was basically brushed on the screen/gently scrubbed until the whole screen was done and then it was hoses off with spray nozzle, thatís basically it you just need to be careful as the screens can easily be damaged if youíre too rough.

    Mine was done whilst my drum was being repaired (busted motor), but Iíve been told by several people that it can be done safely with the drum still in place in your setup as you use so little acid, and to clean it off you just put it on a wash cycle and the acid will disperse into the water.

    My drum doesnít have a uv in it though so over time it does get a build up of muck on the screen, if you have an amalgam uv in shining on the drum screen I think this alleviates a lot of this.


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  19. #15
    Quote Originally Posted by kikokuryu John View Post
    Is enough space available for a larger/longer bulb?
    A tad yes, my lamp is probably just over half the length of the drum chamber.
    There are various places you could mount one, two or more. I still donít get why youíre worried particularly.
    You could just buy the next model drum up which would be the cost of another amalgam UV more or less, especially if you ask for a bit of discount.





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  20. #16
    Quote Originally Posted by bigcarpchaser View Post
    A tad yes, my lamp is probably just over half the length of the drum chamber.
    There are various places you could mount one, two or more. I still donít get why youíre worried particularly.
    You could just buy the next model drum up which would be the cost of another amalgam UV more or less, especially if you ask for a bit of discount.





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    Not really worried, just interested what size of uv will fit inside.

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  22. #17
    Extreme Koi Member Rank = Mature Champion pip895's Avatar
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    Quote Originally Posted by bigcarpchaser View Post
    Hhmmm...isn’t the rule of thumb that a 4” bottom drain can flow around 20k litres/hr at a push?
    I would say more like 12k unless you are prepared to have a large head loss with all the inefficiencies that that brings with it.

    Its worth being aware that max capacities on drums are much higher if you pump feed and it's these values that are often quoted. To run at 30k ltrs I would want 3x 4" inputs and if I was going on to a gravity fed bio chamber I would want 3x outputs too. If pumping directly to a shower you can get away with less outputs though. Extra capacity is good if you realy want to run at 30k then going bigger is a good idea.
    6000g in ground koi pond
    +3000g lily/Anoxic pond attached
    29 koi (40 to 65cm)
    Bottom drain, Mid water & Skimmer to Drum
    JBR boichamber->Blue eco 500 pump ->below surface return.
    Blue Eco 240 -> Large MB -> Waterfall -> Planted Anoxic pond (25 baskets)

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  24. #18
    Ta Pip

    Where have you been hiding yourself these days?


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  25. #19
    Moderator Rank = Supreme Champion Feline's Avatar
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    I never bothered to buy the 3" and 2" flow meters I would have needed to know how much flow I'm putting through my 55k combi, so I don't actually know what the max would be! I have a Flowfriend pump to the shower, and an Aqua Forte 20k variable one on the heat pump line.

    In my setup the limiting factor if I turn the pumps right up is actually the lower shower tray (it's a spigot pipe underwater return type tray) would overflow and there would be a lot of splashing from top and sides of the shower since it creates a total torrent. I've not had any problems with the drum not keeping up tho. I have 2 bottom drains and a 3" gravity fed skimmer input to my drum.

    I once forgot to open one of the BD valves after I had purged them and drum turned itself off because the low water level sensor in the clean side triggered, so I guess that must mean I am pulling way more than 20k lph through the combi normally.

    There are 2 factors to consider really with drum sizing:

    1. Having a big enough max flow to cope with whatever you might want in terms of turnover so you don't end up wishing you had bought a bigger drum in the future. A 30 min pond turnover would be my rule of thumb here and is what I went for.

    2. Speaking to Mike Snaden about this before I built my pond he suggested that you also don't want to oversize a drum, because if you do there will be a long period of time between screen washes, and waste will sit in the water course for longer. He believes one of the massive benefits of a drum over other mechanical filters is that it physically. takes the waste out of contact with the pond water very rapidly, so ammonia etc. in the waste poo is no longer in your pond within minutes.

    So I suppose there is a 'just right' size for each pond!

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  27. #20
    Quote Originally Posted by Feline View Post
    I never bothered to buy the 3" and 2" flow meters I would have needed to know how much flow I'm putting through my 55k combi, so I don't actually know what the max would be! I have a Flowfriend pump to the shower, and an Aqua Forte 20k variable one on the heat pump line.

    In my setup the limiting factor if I turn the pumps right up is actually the lower shower tray (it's a spigot pipe underwater return type tray) would overflow and there would be a lot of splashing from top and sides of the shower since it creates a total torrent. I've not had any problems with the drum not keeping up tho. I have 2 bottom drains and a 3" gravity fed skimmer input to my drum.

    I once forgot to open one of the BD valves after I had purged them and drum turned itself off because the low water level sensor in the clean side triggered, so I guess that must mean I am pulling way more than 20k lph through the combi normally.

    There are 2 factors to consider really with drum sizing:

    1. Having a big enough max flow to cope with whatever you might want in terms of turnover so you don't end up wishing you had bought a bigger drum in the future. A 30 min pond turnover would be my rule of thumb here and is what I went for.

    2. Speaking to Mike Snaden about this before I built my pond he suggested that you also don't want to oversize a drum, because if you do there will be a long period of time between screen washes, and waste will sit in the water course for longer. He believes one of the massive benefits of a drum over other mechanical filters is that it physically. takes the waste out of contact with the pond water very rapidly, so ammonia etc. in the waste poo is no longer in your pond within minutes.

    So I suppose there is a 'just right' size for each pond!


    I don't plan on aiming for a 30 min turnover, an hour turn over is the target I'm after. Perhaps 75 mins. So going off a 35000lph drum figures this should do what I require of it for a 34000 litre pond.

    Currently the water is good, but being able to get it better with less maintenance seems like a no brainer. But deciding which one to get when so much info I don't fully understand is mind boggling.

    I need to get it right as I don't want to regret getting the wrong one.

 

 

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