Getting enough CO2 into the tank

Hi all,

I haven't been on here in a few weeks... work has been busy, so barely enough time to do the routine fish keeping, let alone talk about it!

So, some of you will have seen my 300L planted discus setup. I've doing EI fertilisation and I have a _gut feeling_ that I'm not getting enough C02 into the tank fast enough. I have a couple of issues. Firstly, the drop checker takes ages to actually change colour, and I think it might be green, but it could also be black, blue or any other range of colours (I'll reference you to a dress which has people up in arms about colours recently... it's not that easy to give an exact colour!). I'd like to try getting it to (almost!) yellow and then pare back. I changed my diffuser a few months ago (my old one broke) and I think this has been negative.

In light of this gut feeling, I was strongly dosing with Easy Carbo, in the ignorance that it is not liked by vallis. My extremely strong and 7+ years worth of vallis has died back almost completely. Yesterday I pulled it all out, stripped back all of the dead stuff, through out about 25 plants, and replanted about 12 plants in the hope that it will grow again. This is quite disappointing, given that I have been stocking my LFS with 30-50 plants every 6 months or so!!! All other plants doing _ok_ but not wonderfully. EasyCarbo was also treating an algae issue.

So a few questions:

1. About the drop checker - any better ways of measuring this?
2. Regarding diffusing (remembering I'm using an internal filter, so I can't do any fancy external stuff), any ideas on good diffusers/atomisers/etc (see some options below which you may have some experience on).
3. Anything else I could be doing here?


I'm conscious that I can't put non-advertiser links here, but the options I have narrowed down for diffusers are:
a)Pollen Glass CO2 Diffuser for Aquarium up to 500l
b) Precision CO2 Atomizer 70mm Bazooka Diffuser for Aquarium up to 300L
c) Easy Aqua 4 in 1 Super Atomiser up to 300L

Any experience or comments that you might like to add?

thanks!

one extra point which I forgot to put in...

I'm using rain water which has a PH of about 6.8. I'm using CO2 which lowers it to about 6.3. I think I need to go further with the CO2, as my post above, and in this case I'll need to buffer the water up so that I can do that. Below is a post on this (aquaticconcepts.thekrib.com/Articles/PAM_Discus.htm)... what do you guys think? My rainwater would be similar properties from the barrel.

thanks!


Softer Water

We are lucky to have very soft water directly from the tap. Our water comes from mountain reservoirs and is primarily snow melt. It averages about 0.5 to 1 degree General Hardness (GH or calcium/magnesium hardness). This level of calcium hardness may be fine for a discus-only tank but we feel it is too low for good plant growth. We add calcium carbonate to boost the GH to about 2 degrees. In our 100-gallon discus tank, this works out to about 4 teaspoons (8 grams) of reagent grade CaCO3.

Note: For reference, two teaspoons (about 4 grams) of calcium carbonate per 50 gallons of water will increase both General Hardness (GH) and Carbonate Hardness (KH) by approximately 1 degree. One teaspoon (about 6 grams) of sodium bicarbonate per 50 gallons of water will increase KH by about 1 degree and will not increase GH. Always use a test kit to determine if you are adding enough hardening agents - it is very difficult to get accurate measures of dry chemicals without sensitive laboratory scales. With most common aquarium test kits, 1 degree of hardness (dGH or dKH) is equivalent to 17.8 mg/l of CaCO3, the standard for measuring hardness.

Lower pH

Even though discus are thought to prefer lower pH values, we like to keep our display tanks around pH 6.9. For us, this means adjusting KH and CO2 levels to achieve the desired pH. In a non-planted situation, various commercial pH-adjusting compounds could be used to adjust pH. However, these usually contain phosphates and will lead to algae problems in a planted tank with higher lighting and nutrient levels.

To set the pH, we add sodium bicarbonate (NaHCO3, common baking soda) to increase the KH of our tap water from 2 degrees up to 4 degrees (the equivalent of about 70 mg/l CaCO3). Note that the calcium carbonate added earlier to increase GH will also increase KH; always check KH after increasing GH to see how much sodium bicarbonate you need to add. In our case we add 2 teaspoons (12 grams) of reagent grade NaHCO3 to get a final value of 4 dKH.

Note: Most KH test kits actually measure total alkalinity. If carbonate is the only buffer in the water, total alkalinity equals carbonate hardness. If there are other buffers in the water, such as phosphates, you will not get a true KH reading from a KH test kit. Plan accordingly.
The second part of the pH equation is CO2. When KH is increased, pH will also increase. To bring the pH back to where we want it and to provide plants with enough CO2 to grow well, we inject CO2 to achieve a concentration of 15 mg/l. That concentration of CO2 and 4 dKH will set the pH at 6.9. There are many copies of the KH/CO2/pH tables available on the Internet so you can juggle the KH and CO2 to suit your own requirements. We recommend that you do not exceed a CO2 concentration of more than 15-20 mg/l with discus.

We prefer to use a pH controller that measures pH in the tank and turns on or off a solenoid to control the flow of CO2. With care, you can use a manually controlled CO2 system to do the same thing. After getting the KH to the right level, simply adjust the CO2 flow until the tank has the pH that you desire.

What solution are u using in ur drop checker

bromo blue + 4dkh water. Pre-made solution purchased rather than homemade.

the one I used was jbl I think a premaid solution that u just drop into the dropper which was very good

I haven't had a problem with my Co2 yet.
Color is always easy to read, I use this

www.seahorseaquariums.com/Blau-Glass-C02-Indicator//4777

with purchased 4dkh water mix

Co2 inject ion in done via a Co2 reactor,
something like this (www.drsfostersmith.com/product/prod_display.cfm?pcatid=9918)


but does take about 2 hours before the color stabilizes on my 750 liter

thanks.

Maybe I over-egged the colour issue. I suppose my issue is what's green. There are about 50 shades (!). So while mine does go green, am I sure it is the right green? Could it go "greener" - I think it could! I'm using that drop checker and a pre-mixed solution.

I can't use that reactor, as it's an external in-line one. Anyone else got experience of in-aquarium diffusers/etc?

OK, I've purchased this one:
Precision CO2 Atomizer 70mm Bazooka Diffuser for Aquarium up to 300L

Based on reviews, etc. I also bought myself a new pollen glass diffuser - much bigger than my current one in case the above one doesn't work. but I'm hopeful. I'll let you know.