DIY C02 this cant be right!!!!

[swannee]

I set up a 2 2 litre bottle C02 rig on a 72 gallon tank on thursday afternoon about 1 or 1:30 pm. I used a mix I got off the net somewhere (1 cup sugar, 6 cups warm water, 1 tsp yeast, and a tsp baking soda) hooked it all up to the pick up of a Fluval 304 and not ten minutes after it was all hooked up I started seeing bubbles, so I tested the PH & KH at about 2:30pm and got these results PH 7.2 KH 7 and going by the chart I have that's about 13.3 ppm of C02, 6:30am friday PH 6.8 & KH 7 thats about 33.3 ppm, 6:30pm friday PH6.8 KH 10 thats up over 40 ppm. Fish seem to be doing fine still eating well. And I might add I am using a spraybar near the top of the tank so I have a far bit of surface movement so I should be losing a far bit, and from what I read 2 2 litre bottles won't hardly keep up with a 55 gallon tank, these readings can't be right, can they?

[Spar]

DIY got my 50g up to 30ppm during its first couple days of production (after letting it sit out for 24 hours though). So, it is "possible". However, you said you setup the DIY and immediately hooked it up to the tank? Actual co2 production shouldn't start for at least 12 hours after setting up from what I understand. Maybe it can though if you are already getting the decrease in pH.

Your main problem in the 72g is going to be that it is hard to keep the co2 production consistent and at a high enough level to satisfy the tank. Have you considered pressurized yet? It took me about 2 weeks of DIY to finally throw in the towel and get pressurized. Very little maintenance; other than a pricey intial setup cost, it is virtually free afterwards, with pretty much only a $12-$15 charge for a refill once a year.

But, it is good experience to use the DIY at first IMO. Keep an eye on the pH and see how long it takes in whatever intervals for the co2 production to start declining. Keep shaking the bottles up every couple days to ensure it doesnt crash.

Good luck!

[Rex Grigg]

I doubt it's right. Your kH keeps going up which should not be happening. What are the parameters of your water source? Take a water sample. Let it sit out for 24 hours and test it. It should come out with about 3 ppm of CO2. If you get more than that then you either have bad test kits or other buffers in the water.

[swannee]

Yes I have thought about but here in australia it would cost $800.00 or more, and to make matters worse I am an American so the high cost of living here is harder to cope with, than being a Aussie not not knowing the differance!

So I figure for now I'll stick with plants witch don't have such big demands, so even if the C02 levels are low if and when I can get things on an even keel it's still better than none at all.

Everything I have been reading says the same 6 to 12 hours, and also says 2 bottles would never see 20ppm in a 55 gal tank, and I have found 3 differant charts that at any givin PH/KH all show differant C02 levels, so I'll play with it until I hit something that works.

Thanks for the info Spar

[swannee]

Hi Rex, Just let me start by saying your web site is the most informative site I have seen! Really GREAT JOB!! as for my water source KH & GH 1 drop done deal so my KH is 1 or less and PH is 6.8 Chucks Planted Aquarium Calculator gives me a C02 level of 4.8 and to make maters worse the tank has been set up for a year or so (wife bread Angels) the tank had 8 neons 3 clown loaches and as many as 100 Angel fry in it. so at that time I was using a KH powder that is suppose to raise carbonate hardness by approx 4dkh and helps ph fluctuations, but did a hugh water change (all but 2 inches in bottom of tank) and the following day did half the tank, before setting up the DIY C02 gen. (found the set up in a google search and it turns out is off your web site) At 10am today the KH was 1 PH 6.8 so about 4.8ppm C02 and at 4:30pm KH 9 PH 6.8 so C02 are high again (going by test that is) around 42.8. So clearly either the water changes didnt remove all the buffer that has been added for the past year (KH powder) or the water source (tap water) has other buffers in it as the C02 levels are in the 4.8 or so range, or both! the question is what do I do now?

[Rex Grigg]

Do you have any rocks in the tank? What is the substrate made from? You need to test all these materials to see if they are carbonate containing.

[swannee]

The substrate is course sand 1.5 to 2 mm from LFS and yes I have a rock or two fished out of the Yarra river here in Victoria AUS so I cant really say if they are carbonate containing or not but wouldn't think so but PH test kit is kinda old, year or so, so Ill pick a new one up. I am using Terta's Flora Pride other than that tap water and Water Ager CN

[anonapersona]

With your water source with KH = 1, you will need to be very careful to keep the buffer up. Probably the acidification of the water by the CO2 helps the sand tht contains sea shells to dissolve, raising the KH. Great for now, but one day that may change. You'll need to keep a close eye on that.