Re: Carbo plus vs Co2

[Dan Dixon <dandixon at mac_com>]

Hans & Tina at schaare4 at earthlink_net wrote:

> Now that I have the Co2 set up at a rate of about 35 bubbles/sec

Hans, you probably mean 35/min? If not, what brand of strobe light are you
using to count them?  ;)

> a lot of the plants have been growing well and I've even seen pearling.

You don't describe how much pearling you're getting, but in a tank with
20-30 mg/L of dissolved CO2, ample light and balanced nutrients, the
pearling should look like a tank full of 7-Up by the end of the day. In my
tank, constant streams of bubbles flow off the leaves, and when fish bump
the leaves, masses of bubbles explode loose. It's not subtle.

> But, and here it comes, after a growth spurt a lot of the plants have been
> melting from the edges....I know the tank must be limited on something, I have
> TMG on hand Seachems Potassium supplement, Nitrite-stump remover, epson salts
> ect.... My tank parameters are after several hours of coo on: 260 watts vho,
> on for 9hrs afternoon to evening

Pretty high level of light. Your plants would probably pearl at a pH of 8
and zero bubble rate with that much light. Note that the old rule of thumb
about 3 to 4 watts per gallon applies to normal-output lights. You may have
the equivalent of 5 to 7 watts/gal, depending on the efficiency of your
lights. Your photoperiod could stand to be a little longer, but maybe the
intensity negates that.

> Co2 35 bbls/sec on with lights when lights are out, areation with air pump

You don't say how close to lights on/off you start/stop CO2 injection and
areation, but if it's synchronized exactly with the lights, your plants may
be wanting more CO2 than available right after those times. In my tank, it
takes at least half a day to raise CO2 levels to 25 mg/L from the normal 5-6
mg/L starting point. I also suspect that plants may still want some CO2 for
a short while even after lights go out. I dunno, I'd probably ditch the
areation if it were my tank. It's driving CO2 out of your water that the
plants could benefit from first thing in the morning, and since you're
cutting off the CO2 it may be creating a larger pH swing than it would
otherwise. Personally, I prefer to leave CO2 on 24/7 and inject it at a rate
which will drop pH to about 6.8 by morning, then by the end of each day the
pH will climb to about 7.0 due to plant consumption of CO2, and the cycle
starts all over again. No muss, no fuss.

> 75 gallon
> gravel is 50/50 flourite and gravel
> PH 7.4 - 7.6
> KH 4-5 dkh or 71.6ppm
> GH 8-9 or 143.2ppm

Assuming your test kits are good and there are not significant levels of
non-carbonate buffers in your water to whack things out, it appears you're
not getting enough CO2 into the water (6mg/L max). Your pH/KH ratio is about
where my water starts right out of the tap, before any injection at all. I
like to shoot for between 15 and 30 mg/L.

> Water here is pretty hard even with more Co2 the ph has not gone down
> past 7.4

That's probably because your driving CO2 out with aeration, and the lights
are making the plants burn through CO2 faster than you are injecting it.
Once you close the barn doors, crank the bubble rate up to whatever it takes
to get the pH down to at least 7.0; 6.8 is even better. If you ditch the
aeration and eliminate surface turbulence, I'm guessing about 50-60/min (or
1/sec, no strobe needed) should do it.

> I have TMG on hand Seachems Potassium supplement, Nitrite-stump remover, epson
> salts ect. I need some good advice on how to start of dosing and how much.

Once you get the CO2 right, the nutrients will get consumed at a higher
rate, so get that right first, then you can figure the rest out.

Dan Dixon

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