I never assumed you were going to put an internal one in
I am open to many methods whether I like them or not. Shame on the others. lol
Although many will say you need 2 or more diffusers I would suggest they are people with poor flow/circulation. You sound like you have a decent amount but 2 x1200 = 2400 which is only 6x the volume of a 400l tank.
However you have options still.
I wouldn't suggest a reactor because that would reduce your turnover more. I would say either a Rhinox 5000 which is what Jimboo uses in his Vision 450 journal and position it where your faster filter is hitting the glass hard which will disperse the bubbles better. Its then about maximising the flow to make sure that the bubbles get all around the tank.
Great thing with CO2 and bubbles is you can instantly see the flow from where the bubbles go. lol.
The other option is the Boyu inline which I am using internally. It is very versatile in that it can be used several ways:
option 1 : fitted inline on the filter outlet hose
option 2 : fitted in the tank as the filter outlet
option 3 : fitted to a powerhead internally
Option 1 : With this unit you need good flow out from the filter as the filters output is what is pushing the bubbles out!!! best to fit the unit as close to the filter's powerhead as possible to maximise the amount of hose the bubbles travel along and therfore increase the time they are in contact with the water. then it is important that the bubbles that do come out (some will obviously be 100% diffused within the hose but a lot will survive to enter the tank) are blasted out.
I tried this method with a glass Lily pipe and it didn't work with a single 6 x lph filter (EX700 on a 125ltr). The wide angle of the Lily pipe meant the bubbles gotto the surface very quickly. Your filters are more powerful than mine though. Zigt used this diffuser in his mountainscape V2 setup but he used an ADA jetpipe as his outlet.
Option 2 : Although this is pictured as an option on the box I didn't try it. I have 1 filter and therefore want max flow horizontally. The unit can be used sideways but as I haven't tried this way I have no idea how the flow would be or how well the bubbles would move.
Option 3 : This is the method I am using. This is not detailed on the box and I am using it the wrong way around according to the instructions. They suggest in the pictures that the above are the 2 options you have whereas Instead of using the diffuser as an outlet I have actually connected via some hose to my Maxijet MP400 inlet. I am of course using the supplied strainer so that the shrimp don't get sucked in. lol Works a treat for me but then I only have a 125Ltr tall. This could be used with a more powerful powerhead and at whatever depth you choose. I have mine setup in a C formation rather than upright and therefore in theory I could set the whole thing down near the substrate just as a filter inlet can be and inch or 2 from the bottom. The problem is the powerhead outlet being so close to the bottom means the output will move the substrate (I have sand.) the other beauty of using powerheads is that they are much cheaper than filters, have no flow restriction and they can easily be hidden if you have areas of nice tall growth.
In summary for £5 inc shipping the Boyu is worth a try for anyone and a standard powerhead (UGF type) is cheap. Try all the options with these to assess which works best.
The option is the Rhinox 5000 route which should work fine. Jimbbo uses it and we know how lush his scapes are.
The reason there is such a lack of guidelines on tank volumes is because in the rare cases that someone does suggest a size they are nearly always wrong. they tend to advise too big a diffuser for the size of tank. i.e. I have a Rhinox 2000 in my cupboard which I can get to work fine and get the desired ppm with no problems BUT I didn't need to get it. I could've gone with what they suggest is a Nano one and got the same effect for cheaper and then the pressure would've used the whole disc instead of half (this is only an aesthetic thing. It doesn't matter if it only uses 1 pore of the disc if it gets your ppm right)
The final thing in a larger tank is that I would get 2 or 3 drop checker and put them around the tank so you can see that the CO2 is spreading around. Chameleons as I was saying on UKaps are now available at £3.50 each including shipping off ebay. (These are sold without the 'solution' that is no use to us anyway)
AC
/www.thegreenmachineaquatics.com/mal...0Reactor%201000
