Setting up in line equipment

willjones

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18 May 2008
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Just wanted to share my experience of setting up a planted aquarium with external filter, UV steriliser and in line CO2 and heater.
Some of this may be obvious, but because I ran into a few problems, I thought I’d post my experiences here.

Problem 1 – Reduced flow from canister filter
I was annoyed by my filter not pumping as fast as I expected!
I’ve discovered by research and trial and error, that the biggest factor affecting flow rate from my external filter is the resistance to flow to the input of the filter. Points that create resistance are any elbows or constrictions in the intake pipe. I would advise 2 intake strainers, which can join to form a common intake pipe for the filter, and to avoid any elbows between this pipe and the filter. This effectively halves the resistance to flow in the intake strainers (where all the elbows are). Also all inline equipment should be placed on the outflow side of the filter (this does not seem to affect flow all that much).

Problem 2 – How to inject CO2?
Looked at ugly and cumbersome diffusers, wasn’t happy!
I’ve discovered that if I release the bubbles straight into the intake of the filter, I don’t need a diffuser! There are no bubbles coming out of the outflow, so I’m assuming that all the CO2 is dissolving (using Eheim 2026 filter).

Problem 3 – Buying a UV steriliser that can cope with the flow rate of my filter
Using the bucket and watch method my filter pumped at 685 lph (72% of quoted flow rate). Getting a UV unit powerful enough to kill pathogens meant expense, bulkiness plus wattage. I would advise splitting the flow on the outflow. With this method a relatively small and low wattage UV unit (like helix max 9W, max flow rate 500lph) should be more than adequate to deal with approx 50% of the output flow. This has worked killing off the white-spot on my cardinal tetras.

Problem 4 – Water changes
Haven’t perfected this yet. Not keen on a python as I don’t want to add chlorinated water direct to my aquarium. However, I think it is well worth putting a T connector in the intake pipe with a tap on the end. Connecting this to a hose, I’ve found this a very easy way of emptying water from the aquarium. This can also be used to fill the aquarium by putting connecting the tap to a hose from your water preparation tank and turning the filter on.

Here is a diagram of the set up I currently have (and seems to be working pretty well).
aquariumsetup.jpg

Just my thoughts! Would be interested to know what other people think.

Will
 
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I think the drain pipe should be on the outflow side unless your draining outlet is significantly lower than your tank and the siphon in the system never fails. However if you install the drain pipe at the outflow system you can utilise the pump from your external to pump water into the drain despite where the drain level is. And since you've already had a tap install just before the water is return to the tank, you can always direct the water into the drain as needed.
 

willjones

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Yep, I did consider doing that way, but the syphon does seem to drain the tank ok, and the advantage of having this tap on the input side is that you can use the pump to suck water into the aquarium a bit (taking care not to strain the pump).
 

GreenNeedle

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19 Jul 2007
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Just a point on the inline equipment on the outflow.

It is always best to put it on the outflow because then it has already been filtered and therefore less scum will cake up the inners.

You state that it doesn't seem to have any effect on the flowrate being on the outflow side but I can assure you it does. I used to have an inline heater and Vecton 2 UV on my outflow and ditched the UV in the end for the very reason of the elbowed in and outs of the unit reducing flow.

Even if you had a straight line on the inflow if the flow is being restricted on the outflow then this will limit the flow on the inflow.

The UV unit won't in itself have cured the cardinals of whitespot unless they swam through the UV. However improved water quality due to the UV may have and the UV would've done its best to kill any 'unhosted' parasites. I haven't had any problems with the tank though from not having the UV and it also means I have more control of the tank temperature (especially now that we are approaching summer.)

Not having a go. Just though I'd add my $0.02 from relatively recent experience (got rid of the UV 2 months ago)

Andy
 

willjones

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It is always best to put it on the outflow because then it has already been filtered and therefore less scum will cake up the inners
Agreed.
You state that it doesn't seem to have any effect on the flowrate being on the outflow side but I can assure you it does. I used to have an inline heater and Vecton 2 UV on my outflow and ditched the UV in the end for the very reason of the elbowed in and outs of the unit reducing flow.
I think we are arguing the same point here. The solution that I have proposed is that by splitting the flow around the UV unit, you still get the benefit of the steriliser without the increased resistance and consequent loss of flow.
Even if you had a straight line on the inflow if the flow is being restricted on the outflow then this will limit the flow on the inflow.
Agreed again. However, my point is that points of resistance on the intake side have a much bigger impact on flow than points of resitance on the outflow.
The UV unit won't in itself have cured the cardinals of whitespot unless they swam through the UV. However improved water quality due to the UV may have and the UV would've done its best to kill any 'unhosted' parasites.
Yes i'm aware the UV does not affect whitespot on the actual fish, rather it affects other the other stages in the lifecycle probably making it easier to get rid of. As far as I am aware, a UV unit has no effect on traditional parameters of water quality, it only kills micro-organisms.
I haven't had any problems with the tank though from not having the UV and it also means I have more control of the tank temperature (especially now that we are approaching summer.)
Yep, seems to push the temp up a little bit, and judging by the tank temp on warm days, it looks like I'll have to turn it off soon.
 

ceg4048

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willjones said:
...However, my point is that points of resistance on the intake side have a much bigger impact on flow than points of resitance on the outflow.
Hi willjones,
Although this seems reasonable, there is a complication. The law of conservation of energy demands that for incompressible flow through a closed system energy/momentum in = energy/momentum out. Frictional forces or momentum loss on the inlet side reduces the total flow rate through the remainder of the system. Frictional forces or momentum loss on the outlet side reduces the total flow rate that can enter the system. The effect is identical.

Consider a section of straight garden hose with a spray nozzle. Flow through the hose can be controlled either by creating a restriction at the inlet side (closing the spigot) or by creating a restriction at the outlet side (closing the nozzle). The degree of restriction required at either end is the same. It does not matter where in system the restriction occurs. The momentum loss and subsequent flow rate reduction is the same.

Cheers,
 

willjones

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I've read some stuff on the internet about how centrifugal pumps work, and it seems they are far better at pushing water than pulling it. The problem arises when negative pressure causes cavitation and reduces the efficiency of the pump. This can also reduce the lifetime of a pump. I think that this is why it is always recommended to allow pumps to be gravity fed.
Because they are designed to push rather than pull, it seems logical to me that points of resistance would have less impact on flow when placed on the outflow side. I have also noticed this to be true practically.
http://www.fishkeepingbanter.com/showthread.php?t=11711
I know this thread is talking about pond pumps, but I think the principle is the same.
 
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