Convinced, Help with High Pressure CO2 System

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MikeIsOrganic

Aquarium Advice Newbie
Joined
Apr 27, 2008
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I've got a 55 gallon planted tank, and my pH hovers around 7.6-7.8 without adjustment.I think I'm going to go ahead with the high pressure system, but was curious about a few things first.

At hand, I have a couple 5# CO2 tanks and non-aquarium regulators (high and low pressure, from 0-40lbs). They're not currently hooked up for 1/4" tubing, but I already know of a way to fix that. What pressure do I need to keep it at?

What else do I need? From what I've gathered, a needle valve and a reactor to diffuse the CO2 into the aquarium. I know I'd need to be cautious about the pH too, should I somehow rig a pH meter onto it to shut off when the pH drops too low?

I've been reading around a few sites, but the ones I've come across seem light on specific info or contradict each other. any good resources would be appreciated too.

Thanks!
 
YOu need a solenoid so that you can turn your CO2 on and off.. You could get a pH controller to hook up to this solenoid so that it will kick on when your pH rises above a certain point. I don't use a pH controlelr but lots do.

The way it works is you set it to what you want your ph to be, then it keeps the co2 coming until it is lowered to that point, and shuts it off when it gets lower than that point.

You also would likely want a drop checker, with this, you can put pH reactor in it and by the color, tell how well your getting CO2 into the water.
 
The solenoid and pH controller are bonus, not required.

The equipment you have will work. Standard tank, standard regulator. Like you said, you will need to get a needle valve for fine tuning, and a bubble counter is preferred as well to help you monitor the flow rate.

I run my regulator low side at 30psi, then use the needle valve to close the flow down to ~3bps (bubbles per second as read through the bubble counter). If you can adapt in a needle valve, bubble counter, and adapter for 1/4 or 3/16" tubing, all you need at that point is test kits to measure kH and pH. Set your bubble rate to 2bps and wait a day, measure and calculate your CO2 level, then fine tune things from there.

Or, as Pitt mentioned, you can get a solenoid and pH controller, and let that control the CO2 injection for you.
 
Can someone explain the difference between high side and low side pressure on a CO2 tank?

I'm not ready to go for the full pressurized system yet but I enjoy reading about others' experiences. The low-side, high-side thing has confused me for a while now so I figured I should just go ahead and ask even if I'm not planning to implement that knowledge for a while.
 
The solenoid and pH controller are bonus, not required.

The equipment you have will work. Standard tank, standard regulator. Like you said, you will need to get a needle valve for fine tuning, and a bubble counter is preferred as well to help you monitor the flow rate.

I run my regulator low side at 30psi, then use the needle valve to close the flow down to ~3bps (bubbles per second as read through the bubble counter). If you can adapt in a needle valve, bubble counter, and adapter for 1/4 or 3/16" tubing, all you need at that point is test kits to measure kH and pH. Set your bubble rate to 2bps and wait a day, measure and calculate your CO2 level, then fine tune things from there.

Or, as Pitt mentioned, you can get a solenoid and pH controller, and let that control the CO2 injection for you.

sounds good. I haven't seen a bubble counter in person, are they pretty easy to get a feel for how many bubbles you've got per a second?

What would I be looking for for the kH? and how much dissolved CO2 am I looking for and what would I use to calculate that?

Thanks for the help.
 
Can someone explain the difference between high side and low side pressure on a CO2 tank?

The high side shows the pressure in the cylinder and will read at about 800psi until it's nearly empty. The reason it doesn't drop steadily, is because it is stored as a liquid and it isn't until all the liquid has turned to gas that the pressure starts to drop. The low side is the pressure you set the flow to the aquarium at.

sounds good. I haven't seen a bubble counter in person, are they pretty easy to get a feel for how many bubbles you've got per a second?

What would I be looking for for the kH? and how much dissolved CO2 am I looking for and what would I use to calculate that?

Thanks for the help.

I don't find it hard at all to calculate the BPS, but in my case it's actually a BPM as I'm injecting CO2 into very small aquariums. So I'm usually injecting between 5-8 BPM. Also bubble counters are very easy to build with a childrens medicine shring, a check valve, and a little aquarium silacon or GOOP. I can dig up a thread if you're interested.

You use the KH and the pH to determine your CO2 level. Normally with your pH I'd expect to see your KH somewhere between 4-6dKH unless something else is buffering your pH. You'll want to have about 30ppm CO2. I highly recommend downloading Chuck's Planted Aquarium Calculator, as it makes CO2 and dry fert dosing much easier to figure out. Don't go by his recommended levels though, as they are several years out of date and very conservative.

I also posted a link to this article on setting up Pressurized CO2 in your other thread. I used it when setting mine up, and it was very helpful.
 
Here's a good article: http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

Scroll about halfway down (after you read the article!) to find the CO2/KH/pH table. Above the table is a little calculator that you can plug your pH and KH into and it will tell you your CO2 level. The chart highlights the 10-25 ppm level of CO2. A lot of us run CO2 to hit the 30 ppm mark, especially if the tank is high light. My tank is actually low light so I stick with the 25 ppm range.

What is your KH value now? If you're using a pH controller you need to know your KH before you set the pH controller dial. My KH is 5, so I looked at the chart and determined that I want about 25 ppm of CO2, so I set my pH controller for 6.8, which will give me 23.7 ppm CO2.

If your KH is on the low side (my tap KH is 3 degrees) you'll have to set your pH controller to a lower pH to ensure you're getting the CO2 level that you want. I choose not to run my pH that low. It won't hurt the fish but I don't prefer it in the 6.4 range. I use Seachem's Alkaline Buffer to raise my KH to 5 so I can set my pH controller to 6.8.

If you choose not to use a pH controller, you can run the CO2 concurrently with your tank lighting. Plug your CO2 solenoid into a timer that turns on about a half hour before the lights come on, and turns off with the lights. That way you'll always have CO2 in the tank while the lights are on. If you use this method, it would be helpful to get the CO2 drop checker as mentioned above. The color of the drop checker fluid will give you a visual indication of the CO2 level in the tank.
 
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