# CO2 through external (NW) pump, merge return with main filter?



## Gilles (25 Nov 2014)

I was thinking of adding an Eheim Compact+ Marine pump on a seperate inlet for CO2 enrichment. This is a NW pump (venturi style), followed by a clear water filtering housing to increase dwell time and then join the return with the Fluval FX6 output to the main tank. Would this work?

Returns would be done by means of a Y PVC branch like this one;






Where the top is the inlet of the Fluval FX6, the right branch would be the return from the NW pump and the bottom would be the return to the tank.


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## Gilles (25 Nov 2014)

Maybe @ceg4048 and @foxfish as subject matter experts have a say in this?


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## ian_m (25 Nov 2014)

Can't see your picture.

You should never join pump outputs into a common feed. The failure mode, as one member here found, is that if one pump fails, falls short in output or is simply turned off for tank maintenance, the other pump reverse flows through the filter with pump off and dumps the contents of your filter into the tank via its inlet, promptly killing everything. Nice clean filter though....


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## ceg4048 (25 Nov 2014)

Agreed. Not a good idea generally.

Cheers,


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## Gilles (25 Nov 2014)

thnx, will go for seperate outlets. however; how would i go about this then? I currently have the filter outlet as spraybar across the entire length of the tank facing forward. @ceg4048 how should i position my co2 outlet?
1) At the front of the glass from one side pointing to the other side?
2) Or at the back of the glass from one side to the other side (e.g. behind my spraybary)
3) Change the spraybar so THAT is my co2 outlet, and just put the filter with a knee or something?


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## ian_m (25 Nov 2014)

You will need separate inlets and outlets, to prevent issues.

You could have filter inlet on left, CO2 loop inlet on right and two spray bars, one under the other at the back to the tank, may be point the CO2 spay bar into the flow of the filter spray bar to push the CO2 round the tank.


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## terry82517 (25 Nov 2014)

.


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## foxfish (25 Nov 2014)

Hi Gilles, yes you can join two independently fed pumps into one outlet, the Y section will have to be a suitable size to match the volume.
However, as the guys have pointed out, there are potential problems!
You would need to avoid any back pressure & this really means placing the Y above water level & having an open ended pipe return if you were concerned about Ian's point regarding back flowing.
Anyway, probably not the best idea ....
 I don't really get you logic about using a NW pump & then feeding the mist into a bare canister?
You may dissolve a small amount of gas but there will still be a mist in the tank.


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## Gilles (25 Nov 2014)

Are you sure? I was thinking that the increased dwell time (since the reactor is large in diameter) it would allow the co2 to have more contact time with the water. If i use the clear water filter housing as it is designed (e.g. inflow IN, then outflouw going OUT, but with a pipe to the bottom of the clear water filter) the co2 bubbles have to go down, through the pipe before they enter the tank...


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## foxfish (25 Nov 2014)

You did say " a clear water filtering housing to increase dwell time" you did not say you were going to build a reactor!
Personally, I don't think  it would be worth using a NW pump for that purpose as you could just add the C02 in line?
If you are talking about a 20" vessel, then they are very effective without atomising the bubble first.
However, I am hardly the planted tank police.... I am all up for having fun with equipment


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## X3NiTH (25 Nov 2014)

My dwell time reactor being fed by an inline reverses the inputs and outputs, so co2 injected water first passes through the housing outlet into a long 40mm drainage pipe that I have fitted that is long enough to almost touch the bottom of the inside of the unit, there are two circular sponges that fit the internal diameter of the housing (20" unit) around the outside of this pipe to catch any Co2 bubbles that rise out of the down tube to further diffuse them, the water then exits straight into my tank via the housings inlet, no gas can get trapped this side of the unit. Doing it the other way gas can more easily get trapped in the outer side of the unit and stop flow (or reduce it greatly). Mine goes deep within the down tube first and any rising gas within it will be constantly pushed down by the flow  helping to further dissolve the co2. When priming the unit if there is gas in the down tube it prevents flow, so I always tilt the unit to expel this gas first and then it works flawlessly.

I don't know how well the unit would work with gas piped straight into it, doing it with an inline means the bubbles are already pretty small to begin with and the unit helps to reduce them further to the point that they become invisible to the naked eye. Zero bubbles exit my reactor unit and it's all inline on an Eheim250T, the pumps is rated for 950L/hr and I'm getting about 400+ out of it which probably has more to do with the UV being inline before it and reducing my outlet diameter from 17/22mm to 12/17mm pipe because that's the diameter of the crook I'm using.

I didn't want to drill my unit or remove the pressure release valve (I use this to help prime the unit) which is why I stuck with the inline. If I got rid of my inline I would still try and do the injection without modifying the unit, it's a lot of money to throw down the drain if you break the housing.

It's worth having a shot at it, it's not really that difficult to put together.


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## Gilles (26 Nov 2014)

X3NiTH said:


> no gas can get trapped this side of the unit


Well there you have a point.. At first i was like; both methods (normal or reverse flow) are exactly thesame with regards to water flow, but i now get your point.
With "inline" diffusing, what do you mean? Like with the AquaMedic "T", with an atomizer or with a NW pump?

I ordered a 10" unit, but i will replace that with a 20"; what is the going rate for these puppies in the UK? I have to pay like 80 EUR for them.


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## X3NiTH (26 Nov 2014)

I'm using an Inline Atomiser on mine. Yeah the 20" inch units are about that price, mine is the clear Watts 20" tall, 10" diameter with 1" ports and I paid about £60 for it.


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## Gilles (26 Nov 2014)

X3NiTH said:


> I'm using an Inline Atomiser on mine.


And that works with a cerges reactor? Did you reverse/connect it? E.g. the atomizer connects to the "OUT" of the filter housing and the water to the tank goes out the IN connection of the filter housing?

e.g. this baby?


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## X3NiTH (26 Nov 2014)

That's the one, exactly the same. I didn't get the spanner and it took me and the wife working together to seal the unit shut, not forced and not overly tightened that it cracks the unit (can happen). Yeah the atomiser connects to the out, mine is plumbed 2m before the unit with the hose coiled, so lots of ups and downs first to push against rising gas then into the unit. Eheim double taps make installing the unit easy, the atomiser is before the taps so that I can connect it all back up without the housing and still have atomised co2 in the tank if I have to sort the unit out within an injection period (I should really have the atomiser between a couple of double taps to isolate that if I need to clean it, but double taps are expensive so I haven't done this yet).

Here's the unit.



Here's the top of the unit with the 40mm down pipe attached but not siliconed into place yet, you can see the IN port on the lid (my OUT). To fit the pipe over the OUT port (my IN) I widened the pipe a little and then used the gas hob to carefully heat the plastic enough for me to form it over the outlet for a snug fit.



Here it is siliconed into place.



The down pipe foam came from AllPondSolutions EF-2 Replacement Filter Foam which made a nice sealed fit within unit.


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## X3NiTH (26 Nov 2014)

The filter booster was useless by the way, never could get a tight seal on it.


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## Gilles (26 Nov 2014)

X3NiTH said:


> filter booster


What was it supposed to do? And where did you buy it? I can't find it anywhere at least not for that price (60 quid)

And by the way, isn't 10" (i assume that is the diameter)? HUGE? or is it 4.5? ?


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## foxfish (26 Nov 2014)

Have you any idea how much the flow is restricted by the two sponges?


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## Gilles (26 Nov 2014)

foxfish said:


> Have you any idea how much the flow is restricted by the two sponges?



I think a lot personally. but i haven't ordered the NW yet. I just bought the clear 20" tall housing for now. I have decided that i will be using something like this so before it is delivered (will take some time) i will have answers to my remaining question with regards to flow, because...

I am still debating with myself if i want to remove my Fluval FX6 and switch over to a closed wet/dry sump (in which i can dump my sensors, heater, dosing pump output). I had a sump before and i loved them. Reason for switching would be that i still have a CPR CS100 lying at the attic (brand new).. damn, choices choices....


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## X3NiTH (26 Nov 2014)

Sorry it's 8"across the top, just measured it, don't know why I thought it was 10", as to reduction in flow with the sponges, possibly but I don't know by how much, my pump output is halved from its rated value but that may be down to other things inline like my Helix UV, 3m+ 17/22 Eheim hose (2m coiled) and that I reduce the internal diameter of the piping after the unit so that it fits my crook, so that's a metre or so of 12/16 hose. The sponge is quite coarse but it still collects debris and grows bacteria so the unit needs a clean every now and again. Plastic pot scrubbers were another option but couldn't source them locally, I used the sponges because I had them to hand and they fit snugly so gas couldn't travel up the sides, they would have to go through the sponges where they get completely dissolved. Atomised bubbles do vent from the downtube and the sponge sorts them out so the water is clear as it exits the unit.

I'll be needing to clean the unit soon so I might try to measure the flow through it using the compact+ pump to power it offline.

The filter booster went before the Eheim250T to save me having to put media in it but it wouldn't seal properly and leaked about 1/2L every hour.


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## Gilles (27 Nov 2014)

Any advice on the canister vs wet/dry discussion which is in my head? :0


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## X3NiTH (27 Nov 2014)

Wet/dry sump supposedly provides better oxygenation of the water column over a canister filter, don't have one myself, the injection part of the sump needs to be sealed apparently. This is what I read over on TheBarrReport, there's a monster thread discussing Cerges/dwell time reactors, (where I got the idea for my 20") sumps and needle wheel pumps also formed part of the discussion somewhere amongst it. I had a trawl and couldn't find the link, I'll keep trying and maybe I'll find it. You might have seen the thread I'm talking about, last time I read it it was 40+ pages long.


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## X3NiTH (4 Dec 2014)

Gave the unit a clean this evening and measured its throughput.

The pump used to push water through for measuring is an Eheim Compact+ 2000, all exits for water are through the large 16/22 Eheim Double Taps including pump exit when not connected to the unit for measuring raw pump throughput.

Pump not connected to housing - 1200L/hr

Pump connected to Housing (Before cleaning) - 1000L/hr

Pump connected to Housing (After cleaning) - 1028L/hr

There is reduction in flow, but not massively, the sponges have quite a bit of bio load even after cleaning out detritus and having water running clean through it after many rounds of agitating the unit like a giant cocktail shaker. I'm still happy with my unit and don't feel the need to modify it in any way for the time being. If the sponges fully clog then I will replace them with a coarser PPI sponge or plastic pot scrubs.


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