Hello All.
I wonder if I could ask for some opinions on the fitting of bottom drains.
I will in the next month or so be rebuilding my pond, on paper it's currently looking to be about 5000 gallons 18x7x6. My question is do I fit two bottom drains or just one and have the bottom with steep slopes into a single drain doing away with the problem of having to balance two drains into a single filter. Thanks for any help you can give. Tim
Personally I don't think a steep slope to the drain contributes much to the removal of solids.
I do think that looking at a volume of 5000 gallons you would definitely be looking at two bottom drain if for no other reason that to reach a turnover capacity in tune with that amount of water. That said it will ideally mean having two separate filter systems, one for each drain. People often try to couple two drains to one system but in my experience this usually turns out to be less than satisfactory. If you step back and take a look you will see that it's not as bad as you might first think. Power wise it's not much more expensive to run two, 10,000 l/hr pumps compared to one that does 20,000.
Also consider that you will be pulling a minimum of 15,000 l /hr ( though more would be better) And that is quite a bit to be pulling through a single unit. The security of redundancy speaks for itself.
If however you are determined to go down the one filter two drain route, I find the only satisfactory way of doing it half right is to have both drains feed to a large sump so that the amount of water drawn is slightly balanced. Also try to keep each of the drains as identical to the other as possible in terms of length and number of bends.
ditto everything Scotty and Jules has said .... also take a little time to decide on your pipe work attached to the BD.
The reason being is that I've seen many BD attached to 4" pipe work that ultimately becomes a Hydrogen Sulphide generator and people wonder why their koi are constantly ill. The simple reason being that unless the flow rate through the pipe work is sufficient, all the crud settles in the pipe work and goes rotten.
as an example 3" pipe work (assuming no bends) has a max flow rate of 8700 gph so running anything less than 4000 gph means you run the risk of crud settling out of the water and remaining in the line to rot. (there are ways to flush the line so you don’t have to constantly run such high flow rates – but be aware)
Where as 2" has a max flow rate of circa 3000 gph and 2 1/2" - 5000 gph. and 4â€Â
chris
are you are correct on your flow rate calcs?
if you push through a 2 inch pipe it will go 3000 gals
if you pull from 6 ft down +a couple af 90 deg bends
and through a filter ? my temp lash up i did before
my pond build didnt!!!
note my assuming no bends ... the more bends the higher the lift (read pressure) required by the pump to achieve the max flow of the pump/pipe combination. So a sequence pump is more likely to deliver the rated flow through multiple bends than an aquamax etc. In your example the depth is irrelevant ... the bends arn't
Also when we replaced my liner we changed a 4ft submerged length of hose on the aquamax 10K from 1 1/2" corrugated to 2" smooth and that increased the flow to the nexus 200 from around 1600gph to circa 2000gph - suffice it to say a noticeable difference
chris
we is geting silly !!the original ,post
bott draines 1 or 2. your reply with flow rates ,may lead
him to think fit 2inch to keep clean ! depth sort of matters
if you are 6ft down you have to come up! length off pipe!
and please all bott drain pipes must end up with bends.
my orriginal thoughts were, you need a bigger in than out
cause pulling is diff to pushing
chris yes i did read your post!
my reason for posting was , many bott draines are
hydrogen sulphide genorators , followed by
pipe 2 3 4 2=3000gph. my concern is that a novice may
conclude that a 2 inch will be better as it will pull clean, do
the job better and all at half the cost!! i do not mean to
question your knollege just trying to stop a poss error
i have 2 4inch and 2 filters on 5000 gals so far no problems
due to build up in pipes
Hi Tim,On my 5200 gallon pond I have 2 bottom drains feeding two filters with pumps on both so both are independent of each other.when i recently asked a very good pond builder what if i wanted a Nexus filter instead of what i have now (this was a hypothetical question) how would i balance the flow between the two bottom drains going into one filter the answer was run both drains into a T then into the filter but valve both before the T and then run one drain at a time by this he meant close one off one day and open the next simple and easy to do as we feed our koi every day This may not be the ideal for a new build but for me it would certainly work if i was to change my filters.both drains are 4" pipe work.
Lee,
That is exactly the last way I would consider doing it. Like I said above the two drains into one single filter is at best a balancing act and a precarious one at that. Much better to go the two separate folter route even if it means the filters will be smaller.
Tim,
It's not a row mate, just crossed signals and a difference of opinion. If we meet at the show we can still drink a pint together and have a laugh. Don't let it put you off! Nothing serious!
Hello
Have a little more info to put into the mix,
The new filter I am getting which is second hand is sufficient for 12000 gallons and I currently have a Yamitsu KF 10000, what do you think about running the new filter with a new pump from one drain and running the old filter with an Aquamax 6000 on the second drain. Would it matter if they were not even if the drain nearest the filters ran the smallest filter and the larger filter and new pump ran the furthest drain.
Am I just making things too complicated? Should I just do it and see if it works?
Hi Scotty I would agree not the best way but on an existing system it would work, well one way of doing it.personally i like the two filter route as you can have different medias in each multi media = better filtration
LEE
by this he meant close one off one day and open the next simple and easy to do as we feed our koi every day 
