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Discussion Starter · #1 · (Edited)
Hello Guys,

Just wondering if putting my pressurised CO² directly into the intake (strainer) of my Fluval 205 on my 200L (55G) tank will do a good job of diffusing the CO²?

The reason I ask is because I'm currently running the Rhinox 5000 as the diffuser, but bubbles are only coming out of one side of it, and there are a lot of micro bubbles being blown around the tank and this is making it unsightly to look at, and a fair amount of CO² is just bubbling up to the surface and escaping, meaning the Rhinox isn't doing a very good job of diffusing it.

TIA! :biggrin:
 

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It will work. I have a fluval on my tank hooked up that way just for co2 injection due to gas backing up in my reactor.. You'll get a "burp" a couple of times a day though which will blow some backed up gas into the tank. It's not a mist really, so most of it is just wasted co2. I've heard that bigger canisters have less of a problem with this.
 

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Depending on your bubble rate, you may also reach the point where you're injecting too much for it to dissolve completely in the canister. I was using a 405 for this purpose and eventually ended up with the output misting as I dialed the bubble rate in. It's not as much mist as you'd get with an in-tank diffuser, but something to think about if you're going for a completely mist-less display.
 

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Discussion Starter · #4 ·
So another option would be to get a in-line CO² reactor I suppose.

The reason I didn't want to do this because external in-line CO² reactors are ridiculously expensive, even though all they are is just a plastic shaft with end caps on both ends and barb fittings for hoses. They're over $100 and it just doesn't seem worth it.
 

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I made an inline CO2 reactor for about $15 in parts for my 205. It was so easy and cheap to make, I made a second one. I followed Rex Grigg's design.

The tricky part is accommodating the 205's hoses. I bought some 5/8" I'd vinyl tubing that goes from the reactor to the 205's intake. I ran a shortened length of the 205's hose from my tank to the intake of my reactor. The rubber end of the 205‘s hose is a larger diameter than my vinyl tubing, so I had to adapt it to the barbed inlet of my reactor. 60 cents at Home Despot for the adapter, plus a couple of extra hose clamps and I was in business!

I can show you pix if you would like...

S.Steve
 

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if the co2 isnt coming out of all your rhinow you soak it in a 50% 50% bleach solition and itll clear the ceramic plate and work like new
 

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Discussion Starter · #8 ·
I can show you pix if you would like...

S.Steve
Yes, very interested in this! I was thinking the same thing - how to deal with the 205's ribbed hosing.

Also, do you get any micro bubbles out of the filter outlet?

Looking forward to those pics :icon_lol:
 

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Here is the top barbed fitting. It connects to the 5/8" ID tubing, which then connects to an adapter barb. One side fits in the 5/8" ID tubing, the other fits inside the rubber end of the 205 ribbed tubing. this is the same rubber end that once connected directly to the intake on the canister. Hose clamps keep things secure.


My reactor is currently 14 inches tall, not including the barbs. I do not get any undissolved CO2 leaving the reactor and going to the filter. At the same time, by the time the lights and CO2 turn off at night, I do find that there is some water rushing sounds in the reactor, as if a pocket of CO2 has collected in it during the day. I am wondering if a taller reactor with the CO2 inlet mounted further down on it would lead to more complete absorption. I did mount my CO2 inlet higher up than in Rex's design. I also made the reactor a bit shorter. I should have known not to monkey with a proven design...


Good luck!
 

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Discussion Starter · #11 ·
Cheers Scuba Steve, that's very helpful.

Couple questions tho:

1. How long as your setup been running? Since your intake is directly coming from your tank (no prefilter assumed), aren't you worried that something will get sucked in and clog it up?
2. How noisy (if at all) is it?

I've already had a 'situation' where a khuli loach decided to see what the inside of the filter would look like!
 

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Good questions. The setup has been running for 4 days, so I can't speak of this for the long term. My guess is that if you follow Rex's design (making the reactor longer than mine) you should have no problems.

I have found a kuhli living in my fluval hose before I added the reactor. No prefilter as of yet. I might set one up if it happens again...

In terms of noise, it does sound like some water is rushing through it towards the end of the day. Like I said before, I believe this is because my reactor is not long enough and because I mounted my CO2 injection point too high, allowing a pocket of CO2 to accumulate during the day at the top of the reactor. With the cabinet doors closed, I can't hear it, though. My guess is that it dissipates overnight while the CO2 is off. I'm not that worried about it because I have an airstone that runs at night. Any additional CO2 dissolving into the water will outgas more quickly with the airstone running.

S.Steve
 

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I had a pocket in my reactor also which is why i ran my co2 into the intake for now. I think pump size is the issue. Smaller pumps in the 205 dont create is much turbulence.
 

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I run CO2 inline with the intake. This is all anecdotal as I don't have clear PVC and cannot verify whether or not there is a CO2 pocket.

Last night, I compared the sound of the water going through the reactor to someone trying to slowly pour a glass of water really quietly. No sounds of cavitation with CO2, just almost a trickling sound.

S.Steve
 
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