Are you any good at Maths? I need to work out how many LPH

Discussion in 'Filters, Filtration and Pumps' started by ukapstt77, 27 Mar 2009.

  1. ukapstt77

    ukapstt77 Member

    Messages:
    67
    Hey Guys

    Not sure if this is in the correct section of the Forum so sorry if it's not

    I need to work out how many gallons/litres per hour a 2inch tube will allow to flow through it

    Is there some formula to work it out?!

    The reason I need to know is I'm going to have a total of 8 2inch pipes coming from my 1200g Tropical Freshwater Tank and going into my filter system (4 from the left and 4 from the right of the tank) and I need to know what size pump could handle getting the water back to the tank.

    I've been advised to get something like this (see link and pix below) to use as the filter system as it's low maintenance and has a very high through put flow/LPH. I'll probably get the 12,000 Litre version which is suitable for fish ponds of up to 12000 litres and a maximum flow rate of 7,500 litres ph. They're expensive new but you can get them for a third of the price on http://www.aquarist-classifieds.co.uk
    [​IMG]
    [​IMG]
    http://cgi.ebay.co.uk/Kockney-Koi-Fibre ... 240%3A1318

    The water from the tank enters the side of the Vortex chamber (the round bit at the end) and creates a whirl pool which sucks the big chunks of dirt down the drain and allows the water to escape through a tube at the top into the next chamber. Because it gets rid of the large chunks of dirt straight away the rest of the media further down the filter system doesn't get clogged as quickly so means less cleaning/maintenance.

    Anyway back to my Q's

    Can you please tell me how to work out the LPH/GPH of a 2inch pipe?

    Thanks
     
  2. ukapstt77

    ukapstt77 Member

    Messages:
    67
  3. ukapstt77

    ukapstt77 Member

    Messages:
    67
    I also got this link
    http://www.reefcentral.com/calc/drain.php

    I'm not sure if it's US gallons or UK/Imperial gallons

    Assuming it's UK/Imperial here's my sums
    7500 litres = 1650 uk gallons
    1650 uk gallons divided by 8 = 206.25 uk gallons per pipe
    206.25 uk Gallons per Hour = 0.59 inches drain pipe diameter

    So going by those rough calculations I need 8 half inch pipes to get the 7500lph flow through the Kockney Koi 12000L Filter System. Although I haven't taken into account that 4 of the tubes will be longer and won't be at such a vertical angle as the other 4 pipes nearer to the filter start.

    Can anyone recommend a decent pump that could handle this that has low energy consumption and can be adjusted to different flow rates?
     
  4. ukapstt77

    ukapstt77 Member

    Messages:
    67
    OK I've just redone my calculations to what the guy in the MFK link has as they are for pipes not just a hole:-
    Maximum Gravitational Vertical Flow - This is what we look for when sizing drains or DIY overflows. The flow under the power of gravity reaches a maximum in the same way an object reaches Terminal Velocity as it falls through the air. The gravitational force is countered by the waters viscosity (resistance to flow) and the frictional resistance of the pipe. The viscosity creates a minimum vertical length to acheive the maximum flow. If the vertical pipe length is less than the minimum, the flow rate will be somewhat less than the pipes maximum potential.
    size _GPM __GPH
    1/2 = 2.50 = 150
    3/4 = 5.63 = 337.5
    1.0 = 10.0 = 600
    1.25=15.6 = 937.5
    1.5 = 22.5 = 1350
    2.0 = 40.0 = 2400

    1650ukg divided by 150gph = 11 1/2 inch pipes

    Sorry to ask again but can anyone recommend a decent pump that could handle this that has low energy consumption and can be adjusted to different flow rates?
     
  5. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham
    You seem to be doing a lot of maths here unnecessarily mate!

    Pumped returns mean much more water can be forced through a pipe than will flow through a gravity return!
    My koi pond has a 4" gravity feed to the filter but just 1, 63mm return pipe. I have about 2,500gph (11250lph) flowing through a 25m length of this and it's fine!
    The actual flow rate under gravity also depends on the differential between the two water levels as the inch difference between my pond and the filter's water surface is very different to a filter siuated under the tank!

    If you're working with 2" (50mm) pipe then 1 return will be fine!
    Personally I'd use 1.5" pipe for the return as most pond pumps are designed to deal with that. After the pump I'd split that into two 1.5" returns so you can vary the flow if you want to. Forget getting a pump with adjustable flow, just fit a ball valve on each return and you can just throttle the flow back by closing the valves.
    Two good makes of pumps are either Sequence or Oase Ecomax. Both are very efficient and can be dry mounted after your filter.

    BTW for your filter the one you linked to is not the best you could use and cleaning those brushes will be a pain under a tank. I'd use 3 vortexes and use media in the second and third. These will all drain down dry with their sloping bottoms so no waste can linger there.

    Are you using overflows to feed this filter? If so the number of those may govern the flow rate more than the pipe diameter.
     
  6. ukapstt77

    ukapstt77 Member

    Messages:
    67
    Thanks again Ed for getting back to me

    Yeah I was thinking of just having 1 return pipe

    I'll defenatly split it like you said, I'd like it to go into 3 to be honest, 1 returning water at each end of the tank and 1 leading to the middle back of the tank and going into a huge spray bar

    I'll have to find out what the flow rate is for 3 Vortex linked together is so that I can get an idea of how many pipes I need coming off the tank and at what size/radius. I'm putting holes pipes down each side of the tank, again it depands how many I need but there'll be some 6inches below the surface, some in the middle of the tank and some 6 inches above the gravel.

    I've found this on Ebay
    [​IMG]
    [​IMG]
    http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... otohosting
    Is this what you mean?

    It's got the K1 conversion (I don't really get how this works to be honest)

    Sadly I don't have the cash or room to get it at the moment
     
  7. ukapstt77

    ukapstt77 Member

    Messages:
    67
    I emailed the guy and he said each Vortex holds approx 170gallons, he also thinks the max flow is 3000GPH
     
  8. ukapstt77

    ukapstt77 Member

    Messages:
    67
    Hey Ed

    Looking at these pix of the 3 Vortex I cannot see how the water is taken from the top of one Vortex and put into the next. Surely if they are only linked by the pipe at the bottom that creates the wirlpool the dirt will travle through to the next Vortex wouldn't it?
     
  9. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham
    Each vortex has a 4" pipe feeding in above the cone section and then a 4" outlet pipe near the top of each vortex. The pipe at the bottom is the drain pipe to get rid of the waste water only and this is closed during normal operation.

    With 4" pipe you'll get 3,000gph flow through the pipe.

    BTW you can just get 3 small vortexes and link them yourself with bits of pipe - they may be much cheaper to buy.

    The K1 conversion is a little trickier to do but not too hard. Here is a link to one way of converting a vortex to a static K1 filter, http://www.koi-uk.co.uk/mechanical_filtration_capable_of.htm but anyway that keeps the K1 in while letting the water flow through will work.

    You'll have to have overflows to feed the filter if it's going to be positioned under the tank. Otherwise all the water will drain out of the tank! If the filter's going to be at the same height then you can simply position feeds anywhere as all that will happen when the pump is turned off is that the water levels in filter and tank will stabilise at the same level. Might be tricky to do this inside with a tank though.
     
  10. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham

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