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  1. #1

    Additional bio filter options for after a pump fed easy pod

    What is the best way of adding an additional filter with extra bio media after a pump fed easy pod so it will help with fines and allow for extra feeding if required?

    I was thinking of a multi bay or similar but wasn't sure if that would need to be pump or gravity fed if it's going on the outlet of the easy pod. I was going to put K1 or similar in the bays instead of the sponges, brushes or whatever they come with.



  2. #2
    Moderator Rank = Grand Champion Feline's Avatar
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    You will need to raise up the Pod extremely high, so that it can empty by gravity into the second filter, whch then also needs to empty by gravity into the pond.
    You might find you need a faster pump to cope with the extra head pumping to a raised Pod.

    What you can’t do is fit 2 pumps in series, because their flow will never balance and there is a constant risk of overflow or starving a pump, particularly if one or the other stops working.

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  4. #3
    Thanks for that.

    I remember reading somewhere on a sieve and nexus set up for a pump fed system it was possible to have both at a similar height with a pump before the sieve and another pump between the sieve and the nexus and have a balancer pipe from linked between the sieve and nexus? From memory the pumps had to be different sizes and I think the second pump had to be bigger than the first one? Working on that same principle is it possible to do this set up with an easy pod and multi bay? Would it dictate the multi bay being pump fed?

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  6. #4
    This is what I was referring to. So was thinking if it could be applied to an easy pod and multi bay set up. Basically it looks like the sieve and nexus are set up as a gravity fed system by using a tall section of vertical 4" pipe to act as a fake pond level.

    http://www.evolutionaqua.com/acatalo...pFed_Setup.pdf

    The only thing that worries me is the top of the 4" pipe has a T with an open end !!!!

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  8. #5
    Member Rank = Sansai Brandlin's Avatar
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    Quote Originally Posted by Frimley Koi keeper View Post
    This is what I was referring to. So was thinking if it could be applied to an easy pod and multi bay set up. Basically it looks like the sieve and nexus are set up as a gravity fed system by using a tall section of vertical 4" pipe to act as a fake pond level.

    http://www.evolutionaqua.com/acatalo...pFed_Setup.pdf

    The only thing that worries me is the top of the 4" pipe has a T with an open end !!!!

    This looks like an odd way to solve the problem.

    Imagine that the pump before the UV fails. The pump on the exit of the Cetus will continue to empty the cetus into lower 4" pipe. Because this pipe is open to atmosphere in the nexus and cetus the pump will raise the water level in BOTH (water flowing left to right in the balance pipe) and in the 4" vertical pipe.

    If the UV pump remained off, then the cetus pump will just continue to circulate water around the cetus. It can't exit the system because the water level cant raise far enough in the nexus.

    So, if the UV pump has a lower flow rate than the cetus pump the above happens, with some of the flow from the cetus naturally flowing back along the balance pipe. In this way the system is 'balanced' as long as the flow rate from the cetus pump is HIGHER than the flow from the UV pump. In the event the UV pump has a higher flow rate then it will cause water to bypass the cetus through the balance pipe and straight into the nexus (defeating the effect of the seive).

    The balance pipe picture is a little misleading as you never really want water flowing right to left along it.

    Note that with the differences in pipe size and the relative differences in height of the pumps, simply comparing quoted flow rates on the pumps wont do - you'd need to check actual flow rates in situe.

    It will work, but installing an additional pump, and the inefficiencies of circulating water back through the cetus makes this a difficult solution where resiting the filters to change levels or making them gravity fed might be eaiser.

    If you are starting the system up you would also want to fill the cetus tank with water and start the cetus pump before the UV pump or you will drive unseived water into the nexus.

    I think the open 4" pipe end is to ensure you dont get an airlock in that pipe that might cause flow to be blocked along the balance pipe and therefore for the nexus to overflow and drain the system causing cavittion in the cetus pump. However the way it is drawn with the cetus pipe being open to atmosphere, this does the same job.
    Last edited by Brandlin; 16-05-2018 at 08:41 PM.

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  10. #6
    Thanks, that is a very insightful well explained reply, much appreciated.

    So basically it would work that way but would basically require 2 pumps that you can vary their outputs - something like a pair of aqua forte dm varios 10000 lph pumps and some way of monitoring water flow in various parts of the system in case of pump failures. Basically by the time I buy the multi bay, 2 new pumps, some flow meters, etc. etc. it's probably going to cost a couple of grand at least. For that sort of money it would probably be better to replace my easy pod with a nexus and have 1K change.

    My other options would be to reposition the easy pod so it feeds the multi bay by gravity which might mean I would need a pair of steps every time I cleaned the easy pod depending on where the inlets and outlets are on the multi bay or keep things as they are, monitor water quality and then have a rethink when everything settles down and the K1 fully matures in the easy pod as it only went in on the May Day weekend.

    My current set up is a pond that is raised about 18" from the ground and the outlet from the easy pod is through a 4" brick wall about 22" from the ground so the easy pod is already raised about 20" at least so raising that up much higher would give me two problems, the first being the pump in the pond would need to be upgraded to gain the extra head of water required for the raised easy pod and as mentioned above a step ladder may be required for cleaning.

    Lowering the easy pod and multi bay so it can be changed to a gravity fed system isn't a viable option. Leaving the easy pod at the height it is at the moment and lowering the multi bay is a possible option but would then require a second pump after it which could easily be controlled via a level or float switch in the multi bay in case the pump in the pond failed but would still give me a problem if the second pump failed causing the multi bay to over flow unless a high and low level switch was fitted in the multi bay.

    Help!!! my head hurts

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  12. #7
    Member Rank = Sansai Brandlin's Avatar
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    Quote Originally Posted by Frimley Koi keeper View Post
    Thanks, that is a very insightful well explained reply, much appreciated.

    So basically it would work that way but would basically require 2 pumps that you can vary their outputs - something like a pair of aqua forte dm varios 10000 lph pumps and some way of monitoring water flow in various parts of the system in case of pump failures. Basically by the time I buy the multi bay, 2 new pumps, some flow meters, etc. etc. it's probably going to cost a couple of grand at least. For that sort of money it would probably be better to replace my easy pod with a nexus and have 1K change.
    No problem.

    You dont need variable pumps.

    Just make sure one has higher flow than the other in the installed configuration. The pipework does the flow balancing for you after that.

    Likewise you don't need to monitor flow.

    If the cetus pump fails then you simply get the cetus full of water and water bypassing the cetus and solids in the nexus. If the UV pump fails you simply get water recirculating in the cetus as described above. Neither of those situation is catastrophic so not worth the expense of all the monitoring?

    To run the set up you showed in the picture on one pump, you would need to raise the cetus so that the water level marked in the reservoir below the sieve was level with the water level at the top of the nexus. That way you have pumped input to the cetus, gravity feed to the nexus and gravity return to the pond. So i think this two pump scenario is suggested simply because the operating level of the cetus is so much lower than the nexus - you are effectively using the cetus pump to pump back uphill into the nexus. The alternative in that scenario is raising the cetus some distance.

    I dont own a nexus and am unfamiliar with its specific requirements, however my understanding is it is basically a tank within a tank open to atmosphere. If so then you dont need to raise it above the multibay.

    Gravity feed does not require one tank to be wholly above another. It only requires that the operating water level of the upstream tank is not below the downstream one.The operating levels can be level. For example you cant gravity feed the nexus into your bio filter if the biofilter's operating water level is above the nexus. But it will work if they are level or the multibay below the nexus, even only by a few mm. Remember, water is 'self leveling'.

    Depending on the various resistances to flow of each item of equipment, you may see a reduced flow rate with the water levels closer together, but thats unlikely to be significant enough to require a pump change. You also need to make sure that the capacity for flow downstream of the pump is greater than the actual pump flow rate, but thats the same for all pump fed systems and equipment.

    Feline may have practical experience with the nexus that I do not. And I emphasise that i may understand fluid flow, but i am NOT an expert on the specific equipment. I apologise if feline is right and there is something i have wrong - i will have learned something! and that's a great reason for us all having these discussions.

    Feline is absolutely correct that you cant mount two pumps in series. You will never get the pumps balanced in practice and at best will simply reduce the lifespan of one or both. The balancing line arrangement in the diagram is a way around that issue.

    Certainly though before i spend what could be a four figure sum, I'd want to talk to the people selling you the kit to make sure you have specific advice on the equipment in question.
    Last edited by Brandlin; 17-05-2018 at 10:27 AM.

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  14. #8
    Senior Member Rank = Adult Champion andikoi's Avatar
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    how about this,put a T piece on outlet of pod,one end returns by gravity to pond as you do now,the other end you put a small pump,maybe half the size of your pond pump and feed this to say a small shower,,i run a nexus over a shower and fines arent an issue,andi

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  16. #9
    Yet another well put together reply Brandlin - thanks again.

    You can tell you are an engineer or designer of some description and one that doesn't use all those confusing technical mumbo jumbo terms - nice one.

    At least I wasn't saying I was going to keep koi in an IBC and a blow up paddling pool I have got sort of an idea of what I'm doing - honest gov.

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  18. #10
    Member Rank = Sansai Brandlin's Avatar
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    Quote Originally Posted by Frimley Koi keeper View Post
    Yet another well put together reply Brandlin - thanks again.

    You can tell you are an engineer or designer of some description and one that doesn't use all those confusing technical mumbo jumbo terms - nice one.

    At least I wasn't saying I was going to keep koi in an IBC and a blow up paddling pool I have got sort of an idea of what I'm doing - honest gov.
    Thank you - Someone who uses the term 'Engineer' as a compliment!

    Just wait until I start asking questions about those scaly, wriggly things that I'm supposed to put in the water! I dont know my Nisai from my Samurai, or my Hassai from my katana!

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  20. #11
    Thanks Andi, like your way of thinking there.

    I'm thinking you would use a rubber boot swept T with the straight through to the small pump etc. or the pump may get starved?

    If I can pump from the T I could use virtually any filter for the bio and fines?

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  22. #12
    Quote Originally Posted by Brandlin View Post
    Just wait until I start asking questions about those scaly, wriggly things that I'm supposed to put in the water! I dont know my Nisai from my Samurai, or my Hassai from my katana!
    I'm glad you added that last bit as I thought you were talking about politicians

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  24. #13
    Brandlin - when you've only been on here a couple of weeks or so and have already got more thanks / likes than you have post - you must be doing something right

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  26. #14
    Senior Member Rank = Adult Champion andikoi's Avatar
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    yes put the swept end back to pond,then anything pump doesnt get,the pond will,and yes you could use another filter if you wished,just dont put too big a pump on,andi

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  28. #15
    Bum holes I better cancel my new 50000 lph pump now you've told me that Andi, as I don't want it to suck the easy pod dry do I LOL

 

 

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