In-line carbon filter

[OUsnakebyte]

So, last weekend I decided to take off my UV sterilizer, as I really don't see a difference with it on or off the system. I decided to build and replace it with a larger carbon filter, different than what I have used in the past. The idea was inspired by my RO filter I use to make fresh water with. It looks like this:

 

 

 

It has a 3/4" inlet and outlet with true union valves. The main chamber that is filled with carbon is 3" pvc with rubber reducer couplings to 2", then 2" to 3/4" reducer bushings that fit in the rubber couplings. True union valves are on either side so I can isolate the chamber when it is time to change the carbon.

 

The chamber is packed full of carbon, and I cut circular pieces of filter padding to place on either side of the carbon, so it's not going anywhere.

 

Living in a 1-bedroom apartment, my biggest fear is that I am going to spring a leak on something that will drain to my neighbors below (that happened when I was in college).

 

Sooooo.... what am I missing? Do you think I am at risk of one of the hose clamps failing if pressure builds up in the chamber if it gets clogged? I think (hope) that water will just go the other way if that happens - I should mention this is plumbed into the return manifold of my main system pump (only pump on the system, actually). So, water has 5 ways to go when it leaves the pump.

 

Think this system will even work?

 

Cheers

Mike

[Coral Hind]

Nice job!! I know Sean at AquaCo used to build carbon filters out of PVC similar to that but the rubber adapters are a nice improvement. I don't think they will slip off unless you tighten them down like a girly man. I don't know which pump you are using but most of the pumps we use are not really high pressure pumps.

 

Move topic to the DIY section.

[Origami]

Mike, my only concern over the long haul is the potential for leeching of toxic compounds from the degradation of that black rubber. Daniel Knop raised this concern for saltwater tanks in an article in Coral Magazine in the Jan/Feb 2012 issue.

[flowerseller]

potential for leeching of toxic compounds from the degradation of that black rubber.

 

My first thought too because I know they get slimmey pretty fast..

[Coral Hind]

Could air get trapped in the top 1/3 of the unit since it lays on the side? That would reduce the amount of usable media inside the vessel.

[dave w]

That looks fine to me. A couple of possible changes. I assume the black rubber 3" x 2" adaptors were used for ease of changing media, in the plumbing biz they are called "fernco" couplings.

 

If you're concerned with degradation of the rubber you could line the inside of them with a plastic tube. Just a simple plastic bag with the bottom cut out would minimize or eliminate any contact area between the rubber and the salt water. In theory the plastic won't keep as tight a grip on the outside of the PVC tube, but in reality your pipe clamps will hold just fine. It's not like this thing will be moving much.

 

Second, you could fit straight PVC bushings or adaptors instead of the fernco couplings. This would make it harder to change the media but you could still pull out the filter pad from one end with a coat hanger or something, replace the activated carbon, and then push the pad back on top when you're done. I don't really think that would be necessary, it's more work and I don't think there is enough savings on water quality to be worth the change.

 

If you're concerned about air buildup, you could turn this filter vertically and let water drain through by gravity. The top end would be open and probably more susceptible to overflow if neglected media clogged up, and I think there would be more liklihood of tipping and leaking. But the air issue would be gone.

[Coral Hind]

Mike, my only concern over the long haul is the potential for leeching of toxic compounds from the degradation of that black rubber. Daniel Knop raised this concern for saltwater tanks in an article in Coral Magazine in the Jan/Feb 2012 issue.

 

I don't think the black flexible couplings are a risk. Knop's article was about the cheap plastics that get hard, cracks, and is sooty when touched. I know the Fernco brand of flexible couplings are PVC based and are fine for salt water.

 

http://www.fernco.co...id-resist-chart

 

On a side note I found the article's reference to V2A and V4A out of touch to the intended audience here in the US as they are German standards. I know that's Knop's home country but the article should have been converted to make more sense using the SAE grades of 304 and 316 before releasing it here.

[Coral Hind]

If you're concerned about air buildup, you could turn this filter vertically and let water drain through by gravity. The top end would be open and probably more susceptible to overflow if neglected media clogged up, and I think there would be more liklihood of tipping and leaking. But the air issue would be gone.

 

I wouldn't do it that way becuase it will eventually get clogged and overflow. The filter would also act much like a trickle filter which would become a nitrate factory. If the filter was turned vertically I would leave it sealed and flow the water bottom to top to remove the air.

[OUsnakebyte]

All good thoughts everyone - thanks for the feedback!

 

- I originally wanted to make this out of 3" clear pvc but couldn't find a local source (didn't want to pay shipping for a single length of pvc).

 

- I also thought about turning it vertical but I wanted it to be an easy installation. I figure a verticle setup would be "more involved." It certainly wouldn't be "impossible" just more materials. If I could somehow mount the unit (on the wall or the aquarium) that would keep the weight off the 3/4" connectors, this might be an easy change.

 

- I considered not using the rubber couplings (fernco couplings) and instead using 3" unions, but that significantly increases the cost (~$35 per union). I could still do that though - it would be an easy switch, as would swapping out for 3" clear pvc if I come across a length.

 

- I also thought about lining the inside of the fernco couplings with a layer of aquarium silicone - though... I'm not so sure that's a great solution.

 

But... now that I think of it... I have definitley seen these rubber couplings before connecting bulkhead-to-bulkhead. But, I've never really thought about them leeching materials....

 

How would I even test the effectiveness of this anyway? I suppose I could measure my tank's dissolved organic carbon and then measure the DOC coming from the output of the filter?

 

Cheers

Mike

Edited March 12, 2012 by OUsnakebyte