Combining 2 pumps


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I want to add a second pump to my bio filter. Rather than hooking it up at the filter (requiring extra tubing and another tube coming over the edge, is there any reason this would be a bad idea:

Simply add a T under water and connect the new pump to the existing tube?
The tube is wide enough to handle the flow of both pumps.
Now I wonder if it will cause the pumps to "fight" or not. You would think so, but then if I put that T right at my filter, it would have the exact same result, or not? Im confused lol.
 
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You need the hose off the pump , To be the maximum size of the pump outlet to get the best flow it could put out.
You would need to double that adding the second pump
 
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Im not sure I understand what you are saying, but the more I think about it, the more it seems like a bad idea, regardless of the diameter of the hose (which is wide enough). Ill just get another hose and make something at the filter so I can connect it without the second pump having to fight with the pressure of the first.
 

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Vertigo, What he is trying to say is if each pump has a 1" outlet coming from the pump, then where you connect the two lines together it would need to go up to at least a 2", If they are 1 1/2" outlets at the pump you would need 3" where the two come together.
 
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Not to nit pick, but if thats what he meant, he is actually incorrect. A 1.5" tube has ~2x the throughput of 1" tube, and a 2" has ~4x the throughput of a 1". So even if I was "tube limited", I certainly wouldnt have to double the size.

Anyway, the real problem here is pressure, and thats why its a stupid idea. I have to tube the second pump to the filter and connect in such a way that the only pressure the second pump has to overcome is the height to the filter, rather than height + perhaps 1/2 the pressure from first pump.
 
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Malak said:
Why not have two inputs i.e. totally separate lines that never the twain(sorry Shania) shall meet?
I wanted to avoid that, since its an old concrete pond, so you can see the tubes and they have to go over the edge. That, and to save money :p.
 
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A 1" circle has 3 square inch surface area. A 2" circle has a surface area of 12.5 square inch. Throughput isnt the right word though, as pressure and velocity factor in, but roughly you can pump 4x more water through a 2 inch pipe compared to a 1", at a given pressure and speed.
 
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be sure that the filter can handle the extra water flow as well.

Rule of thumb, gravity returns need to be twice the size of a pumped inlet (1" pump in, 2" gravity out), although adding an extra inch is always advicable. 3" gravity return is good for about 10000L/hr with some extra 'emergency' capacity.
 
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Indeed. Fortunately I do have 4.3 inch (110mm) return and intra-barrel pipes (is that a word lol?), as I planned on this from the start. I just hooked up the second pump (on its own inlet) and as I expected, its borderline with a 15000 L/h + 8000 L/h pump both at ~2 meter head. Water rises more than an inch above the return pipes, and I was stupid enough to position the bulkheads quite high, so water is now only an inch from the edge in my first barrel. Its probably also too much flow to have much benefit from the vortex, so Ill probably put a T on one of the pumps and use some of its capacity to circulate water around in the pond, possibly with a venturi.
 
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was there a need for the increased flow?

stalked your profile, see it's about 50,000l concrete in a bowl type of formation. Assume the bigger pump is in that central recess and the rest of the pond is leaning down towards this point.

Assuming the filtration is coping physically with the 15000l/hr pump, id use the 8000L placed with the output firing straight out the unit, to make a pond current spinning around, turning the entire pond into a vortex with the large central pump taking out this waste to the vortex then filtration?
 
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ginger_biscuit69 said:
was there a need for the increased flow?

stalked your profile, see it's about 50,000l concrete in a bowl type of formation. Assume the bigger pump is in that central recess and the rest of the pond is leaning down towards this point.
All correct. Do I need more filtration? Biologically/chemically, no. My fish load is extremely light for such a large pond, I have absolutely no ammonia or nitrites problem. I probably wouldnt have one without the 15K pump and DIY filter, as there is also a fairly large iris bed (although its in clay and water is merely running over it, not through it. Very poor design, but it is what it is. Its fed by a third pump btw, not sure about the capacity, but I estimate around 5-6000L/hour).

Some Koi have grown huge and survived for decades in this pond with just those irises and that pump. I added all the rest recently, as, well, those koi didnt survive in the end (mass die off from parasites a few years ago) and the entire pond had become a giant mud pool.

Mechanically, I need everything I can get to have any hopes of keeping the water somewhat clear. The pond is surrounded by overhanging trees and bushes, and there is a slope. The amount of stuff falling in is absurd and not all of it floats. But much does, so I really need a skimmer. Ideally Id need many skimmers in fact, but if youve seen pics of the pond, you may understand its not easy to install.

As to this:

Assuming the filtration is coping physically with the 15000l/hr pump, id use the 8000L placed with the output firing straight out the unit, to make a pond current spinning around, turning the entire pond into a vortex with the large central pump taking out this waste to the vortex then filtration?
Thats pretty much what I was thinking, and why I said Id add a T and use part of one pumps capacity for just that purpose (perhaps with an added venturi, although I already have a large airpump with a disc in the pond and several stones in the filter).

A few problems with that though:
1) my waterlilies dont like this idea
2) I already tried it for a while, and the pond is not uniform enough to create a real vortex. The pond is formed like a croissant and the resulting flow is complex. Pumping water around does help, but not like it would in a round pond.
3) im gonna need some pumping capacity for a makeshift "skimming lava filter" that I intend to make in one of the "croissant tips". See here:
https://www.gardenpondforum.com/lava-filter-t7926.html

Now believe it or not, I still have a 4th pump laying around, its a "basement pump". Its extremely powerful, 25K liter per hour or so, but its also a power hog (1000W). So I think Ill use that pump for the vortex, but put it on only a few quarters of an hour per day on a time clock. Then use the 8000L pump for the lava bed/skimmer I have yet to make, and I might as well feed that back to my biofilter. Not sure about that yet.

Anyway, I appreciate your thoughts.
 
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hey, sorry for long reply time, thought id go fullon:




id keep the 15000 as the central main filtration pump, with the return coming out at 90degrees mid depth as pictured.

add a skimmer where pictured with its own 'filter', its just for catching solids so providing it has the basket with some japmat under should do the job. Id put the outlet of this opposite the filter outlet also at 90degrees to promote the circulation of the water volume.

For aeration, id suggest purchasing a diaphram pump of around 75-100l/hr such as an EA airtech75, purchasing a large air diffuser like this : http://cgi.ebay.co.uk/12-AIR-DIFFUSER-DISC-KOI-FISH-POND-QUARANTINE-TANK-/160579554690?_trksid=p4340.m263&_trkparms=algo=SIC&its=I%2BC&itu=UCI%2BIA%2BUA%2BFICS%2BUFI&otn=15&pmod=400210066817&ps=63&clkid=9108009953324574434 , ziptie the diffuser on top of the large central pump, and connect it up with around 15mm airline (would require some inventive plumbing!). This would give you the benefits of an aerated bottom drain - the central uplift pulls debris in the water towards the base of the air diffuser:


Dont use the 25kl water pump, they are designed for occasional use, not constant use. The filter/skimmer combo should be adequate to run the pond, with a third small pump going into the reed bed (only needs to be around 2000l/hr).

Filtration sounds good, if ammonia and nitrite are stable at 0, its perfect. Job done.

Hope this is of help, you are a lucky man having that. Addition of a 55w UVC to the main filter maybe needed sometime when the water clears if it starts to algae up!
 
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vertigo72 said:
Im not sure I understand what you are saying, but the more I think about it, the more it seems like a bad idea, regardless of the diameter of the hose (which is wide enough). Ill just get another hose and make something at the filter so I can connect it without the second pump having to fight with the pressure of the first.
Im saying my laguna 4500 gph has a 1 1/2" Max outlet
if i ran a 1" hose i would not get all the flow out of my pump
The 1 1/2" hose gives me less resistance and the pump can move the water as it was designed for
Two lines would be best
 
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Wow, ginger_biscuit. Wanna come over and do some digging too lol?

Big thanks for the thoughts and the work you put in!

However I should have mentioned I have no intention of drilling through or breaking the concrete. Thats why a wall skimmer is not an option, and hanging something on the edge isnt easy with all the slopes and curves. Especially not where you drew it, as there is a large Japanese cherry tree ~1 meter from where you drew the skimmer. I expect roots :cool:.

I might build something that attaches to the underwater wall on the right lob of the pond though, at least that gives me a straight wall that goes straight down.

Another thought I had last night, is to use water rotation. Before I anchored my air line with stones, it was floating, and I noticed it performed admirably as "skimmer" when I was rotating the entire pond with the 8K pump, or just when the wind blew hard enough. Debris collected nicely against the airline, and then "slid" towards the pond egde, and I could skoop it up easily. Perhaps I should make something working on the same principle, but with a net/basket to capture it. Either that, or I should buy one or two of those floating skimmers with integrated pump. ANything is better than nothing. Not sure yet what Ill do though.

id keep the 15000 as the central main filtration pump, with the return coming out at 90degrees mid depth as pictured.
TBH Im not sure thats a good idea. Already the outflow from the filter seems to go to the pump too quickly. I noticed that when I added some GH+ in the filter. The white clouds in the outflow sank pretty damn fast, almost straight towards the pump. Now the GH stuff is probably heavier than water, but it was stunning nonetheless, and putting the output at half depth would make that worse even. Not too mention a 110mm pipe is not pretty in water.. Im thinking of moving the outflow to the right lob of of the pond instead. That way the filtered water will have to travel over that submerged wall, in to the main pond. Would also help a tiny bit keeping the water rotating.

For aeration, id suggest purchasing a diaphram pump of around 75-100l/hr such as an EA airtech75, purchasing a large air diffuser like this :
I already have a 160L/hour pump (piston I think? made for 24/7 operation with no maintenance) and a similar sized air disc, which indeed, is on top of the pump ;). Thanks for that picture though, now I understand why I had to put it there!. I also have several air stones in the bio filter barrels, and if I do that lava rock bed in the right lob, I will aerate that too to prevent pockets of standing water.

Dont use the 25kl water pump, they are designed for occasional use, not constant use.
True, but I said Id only turn it on occasionally, for 15 minutes at a time, a few times per day. Once the water spins, it keeps spinning for like an hour, if not more. Besides, its already survived ~12h/7 operation for a year prior to my work, when it was used as fountain pump and to keep the pond from freezing over in winter (and to accidentally empty the pond lol). Maybe it wont last, in fact, probably it wont, its already making more noise than in the beginning I think, but it was cheap (Aldi supermarket) and has lasted far longer than one would expect. I could easily pick up another one at Aldi if it lasts 3 years. Thing is, this pump does turn the pond in a vortex that removes debris from the bottom, the 8K pump isnt powerful enough to do that.

Addition of a 55w UVC to the main filter maybe needed sometime when the water clears if it starts to algae up!
hadnt mentioned this either yet, but I picked up a 36W UVC a few weeks ago. I know 36W isnt enough, but I thought it wouldnt hurt either. I wasnt planning on using UVC at all, but the guy that sold me the 15K pump asked me if I wanted it, and I said no, but did a silly bid of 20 euro, and he agreed. Its 6 months old and only been used a few weeks :). Anyway, I put it inline with the pump going to the iris bed as thats my weakest pump. Hoping it will help a bit killing parasites if nothing else.
 
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update: your idea for changing the outflow works brilliantly. I misinterpreted your picture thinking your aim was just to get the flow below water, while you wanted to change the flow direction clockwise.. and of course, that doesnt work well if the outflow is above water, as the water just drops down. I added a few elbows and short piece of pipe, and the water is turning in the entire pond now, gently scraping the bottom clean and pushing all floating debris to a few places where I can put a net/basket or skimmer. Brilliant. Thanks!
 

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