Carbo Plus CO2 and a Controller Question

[theotheragentm]

I'm still deciding on a CO2 method for myself. I have plenty of Excel left right now, but I'd rather not dose and have something automated.

I've seen these before in a LFS, and while they work, they're expensive. I know there are supposed to be versions of this from China that are half the price. Has anyone stumbled across these? How long would a block last in a 55-gallon tank?

The other question I had is how the pH controller feeds back to control the CO2. Based on what parts I've seen on a pressurized CO2 system, it would make sense that the controller is feeding back to the solenoid, but I've never seen a full setup hooked up. Can someone explain this to me?[/code]

[rich311k]

The carbo plus units are garbage. They suck the KH out of your tank and the refills are quite expensive.

I do not have a PH controller but the idea is that when a certain PH is reached the solenoid is turned off stopping the flow of CO2. It is not needed. Once you have the CO2 dialed in you really dont have to worry about it until you need to change tanks.

[theotheragentm]

Originally Posted by rich311k

The carbo plus units are garbage. They suck the KH out of your tank and the refills are quite expensive.

I do not have a PH controller but the idea is that when a certain PH is reached the solenoid is turned off stopping the flow of CO2. It is not needed. Once you have the CO2 dialed in you really dont have to worry about it until you need to change tanks.

Okay. Gotcha on the carbon blocks.

Doesn't the amount of plants in a tank factor into the CO2 levels you want? As the plants grow, don't you have to adjust?

[rich311k]

In theory yes, but I keep my levels well over 35 ppm. That way there is always enough but not to much to harm any of my critters.

[theotheragentm]

Here's something simple I totally missed. Where do you want to keep your PPM generally and when does it start becoming a problem for fish and other critters?

[Purrbox]

Generally CO2 isn't going to be a problem for fish until you hit levels above 100ppm as long as your O2 levels are good. I aim for about 35ppm or a little higher.

[theotheragentm]

I just thought of some questions on a CO2 system.

1. What does the solenoid do if you don't have the pH controller? I'm used to seeing regulators and solenoids on industrial applications. Normally I'd assume the regulator is just cranked down manually, reducing the pressure of CO2 going to the tank, and normally solenoids are on/off in function, but that controls the solenoid if you don't have the pH controller?

2. Is CO2 normally kept on with lights on a timer, and adjusting the regulator until you have your 35ppm in the tank at the end of the light session?

[rich311k]

1. Mine is on a timer. Goes on an hour before the lights do and off when the lights go off. Helps save some CO2.

2. I use a drop checker. As long as it is green I am happy. That and the plants pearl like crazy within a few hours of lights on. If the drop checker turns yellow I back the CO2 down a bit.

[theotheragentm]

So does that mean the solenoid doesn't do anything if you don't have a pH controller?

How quickly will the range change? I am out on weekends a lot of times, away from the tank for 36 hours at a time. I'm trying to see whether this spells disaster for me if I don't get a pH controller.

[dapellegrini]

The solenoid turns his CO2 off at night - plugged into a timer.

Otherwise you are right a pH controller would also make good use of the solenoid.

Many folks out there do not use controllers and are able to balance their CO2 injection with BPS (Bubble Per Second) tweaking with a needle valve. Personally I found that too hard and just use a controller - when on it just blasts CO2 in there until the pH is corrected and then stops. I also have the whole thing turn off at night.

And in addition to the controller I use a drop checker with reference solution to confirm that my CO2 levels are correct regardless of what my controller thinks (great first indication that your CO2 tank is empty is seeing your drop checker go blue).

A controller is going to cost you around $100 if you want to go that route... Without one, you do run a higher risk of killing all of your fish, especially if you are new to CO2 and not around your tanks for long periods of time.

[rich311k]

Start slow and keep an eye on your drop checker. You should do just fine. I would recommend planning on being around your tank for the first day or so to be sure all stays well. I highly reccomend turning the unit off at night. I think you are much more likely to have a leak and waste a tank of gas in a day or so than you are to kill all your fish off.

[theotheragentm]

Thanks for all your help, everyone. I'm definitely getting a mental picture of the whole setup now. The solenoid is a normally closed valve, hooked up to a standard power plug. Does that mean the pH controller is something the solenoid can plug into and the controller will disconnect the circuit when you reach your pH level specified?

[dapellegrini]

Yep. The solenoid plugs into the controller, which will then turn it on or off...

[theotheragentm]

Thanks. I'm used to dealing with industrial applications, where your solenoids have bare wires or spade terminals to hook up to things rather than wall socket plugs. Scaling everything down to fish tanks is the same principle, but it's still very new to me. If anyone wants to build a huge tank with level controls and pumps, I can help you find equipment to do it. It'd probably have to be 1,000+ gallons though before it becomes worth the money.