# Increasing flow in a deep tank



## idris (30 Mar 2013)

I'm about to re-plumb my tank and add a second pump to improve the circulation.The tank is 2'6" deep, and the surface area is just 3.7 sq ft.

In order to improve flow at the bottom of the tank, I've been wondering about having the outlet for one pump as something other than as a spraybar at the surface. Maybe an outlet nearer the bottom of the tank.

Any thoughts?


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## mafoo (30 Mar 2013)

Put a small powerhead at the bottom.


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## idris (30 Mar 2013)

Half the reason I'm putting a second pump in is instead of an ugly plastic lump with a messy wire sticking out of it in my tank.


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## mafoo (30 Mar 2013)

You can get ones where the wire goes on the outside of the tank and attaches via magnets.


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## idris (31 Mar 2013)

Ooh, I like that idea, but it wouldn't work for my tank. (Pictures are in my old journal in my signifies.)

But the question is effectively the same: Should it go towards the bottom of the tank?


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## Ed Seeley (31 Mar 2013)

What are the dimensions of the tank?

If it's a deep cube then I would add some way of getting CO2 rich water to plants lower down in the tank.  You could either have a deepwater outlet to the filter though I would only do this if you have inline CO2 reactor/diffuser as the outlet will put CO2 rich water low down.  If you have a ceramic diffuser in the tank then I'd look at using a filter outlet or flow pump near the surface above the diffuser directing the CO2 rich water down towards the substrate plants.

If it's longer than it is deep then I would just use outlets near the surface but have 1 that will deliver CO2 rish water pointed down towards the substrate to get the CO2 distributed down towards the substrate.


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## idris (31 Mar 2013)

2'6" tall, 12" back to front, and a little less than 4' wide, and there is no added CO2.
I'm most interested in increasing flow in general. CO2 won't be considered for the forseeable future.


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## Vanish (31 Mar 2013)

I have a deep aquarium with an EX1200. Mine probably has to push the water up to about the same height as yours. The problem is that this reduces the output and although I haven't measured mine I would almost certainly say that it's nowhere near 1200LPH. 
I do have two power heads in mine pushing water from the back wall to the front, with the spray bar along the back pointing down at 45 degree. 
I have recently acquired a central heating circulation pump (£5 off eBay) which I intend to rig up and replace the power heads.


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## idris (31 Mar 2013)

Vanish - you're absolutely right about reduced flow. I tested the EX1200 to see what it would pump. I can't remember what it turn over, but with filter media and no head, I know it wasn't 1200lph. 
Do you have a thread or journal featuring this pump? Obviously that's much cheaper than any aquarium specific pump. I'm really curious to know how well it pumps, and how quietly.


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## Vanish (31 Mar 2013)

Makes you wonder where these filter manufacturers got there figures from. 
I got the idea from a chap on this forum. 
Here's a link to the thread. 
High flow DIY reactor - now with video | UK Aquatic Plant Society
I also built the reactor, which work like a dream- super efficient.


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## idris (31 Mar 2013)

Just done some research: was your pump new or second hand? (Can't find a new one for less than an aquarium pump.)


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## Vanish (31 Mar 2013)

2nd hand from eBay. The cheapest new was £35


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## idris (31 Mar 2013)

(That's roughly what I found.)
Bearing in mind the demands on a central heating pump are massive compared to a fish tank, any idea what LPH you can get with just a metre or so of head?


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## Vanish (1 Apr 2013)

Here's link to the user manual for my grundfos pump. Mine is the selectric. 
http://www.oilybits.com/downloads/GRUNDFOS_UPS_SELECTRIC_15-50_MANUAL.pdf
This explains the LPH at the three settings and the head as well.


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## idris (1 Apr 2013)

Thanks. 
By my reckoning it's about 1600lph on the middle setting with 1m of head. Cool! 
Are you aware of any significant issues with cleaning a second hand pump? (I know different additives get put in central heating systems to reduce calcification and air bubbles, but I've no idea how toxic they'd be to fish or plants.)


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## Vanish (1 Apr 2013)

I shouldn't think there would be any issues flushing the pump clear of any inhibitor. When I get it done I'll post results


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## foxfish (1 Apr 2013)

I use an Aqaturn conversion kit on my Grundfos pumps .....  look down the page for performance figures  Aqua-Turn conversion kit for Grundfos Pumps Koi Ponds and Filter LARGE and small | eBay


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## Vanish (1 Apr 2013)

Excellent.  Thanks for that. I'd heard of these before but never seen one.


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## foxfish (1 Apr 2013)

To be honest Grundfos pumps are not the most efficient or economical pumps out there but, I have some that have run for 20 years + & are still going strong.
The addition of the Aquaturn conversion is the secrete as the standard cast iron impeller housing is prone to corrosion & also restricts flow.
I love the three speeds & the silent running reliability.


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## Vanish (1 Apr 2013)

That's what I find particularly attractive, I love the adjustable speed option.  I'll order the aquaturn, it's a brilliant mod'. By the way top marks for the reactor design. I've made one and it is so much better than the diffuser that I had before. I fitted a 8mm John guest fitting to house the CO2 pipe on mine. When I've converted and fitted the pump I'll transfer the reactor to it.


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## Vanish (3 Apr 2013)

Idris I've created a separate post which is related to our earlier posts. 
Central heating pump conversion | UK Aquatic Plant Society
Hope you find it useful.


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## Andrew Dale (4 Apr 2013)

Fr improving the water flow in to and half feet deep tank, there is need of medium size powerhead. I will maintain the flow in this depth of water. 750 gph would be good size powerhead for mostof tanks. But with increasing the gph flow will be more.


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## foxfish (4 Apr 2013)

The only issue would be having too much flow in a low tech tank?


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## idris (17 Apr 2013)

foxfish said:


> The only issue would be having too much flow in a low tech tank?


Too much flow in a low tech tank is a new one on me. Can you elaborate?


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