Stabilizing pH in a 10 gallon

[Jesse]

First of all, I just want to say thanks to all that participate in this forum. I have learned a lot just by reading through various journals and other posts. This site is really an excellent source of info for beginners and experts alike.

I've kept live plants for almost two years now. Echinodorus "Rubin", Spiral Val, and Crypt wendtii thrive in my 70 gal with an UGF and side canister filter. Currently I am 'experimenting' with DIY CO2 on a 10 gallon. It absorbs approximately 3wpg and contains Lobelia cardinalis, Aponogeton crispus, Hygrophila lacustris? (AKA - "Blue Hygro"), Crypt wendtii, Spiral Val, and Nymphaea rubra? (AKA - "Dwarf Red Lily") all purchased from my LFS and no fish yet.

On June 5th I connected my 3L DIY yeast CO2 reactor and diffuser. To start the pH was 7.6 with the CO2 rate about 1 bubble every 13 seconds. Even at this slow rate, I noticed a few small streams of O2 bubbles rising from the leaves. I haven't purchased a kH test kit yet, sorry.

June 6th I noticed only minor growth on a few plants. The pH was still at 7.6.

June 7th I came home from work to find noticable growth, over an inch in some cases especially the spiral val and A. crispus. The pH has dropped considerably to 6.6 with the bubble count to 1 bubble every 1-2 seconds. Not knowing the kH, I assumed the CO2 had to be over 30 ppm and added an air stone to increase circulation and see what happened. Within a few hours the ph was back to 7.6 and constant.

I know I can add baking soda to increase the kH and therefore balance the pH, but is there any known way(s) to regulate the CO2 using yeast?

How many CO2 bubbles per minute is suitable for a 10 gal setup?

I am familiar with the pH vs. kH chart to determine CO2 ppm. Fish are sensitive to pH, but are they affected by the relation between CO2 and kH assuming the resulting pH is constant? I'd find out for myself, but I am strongly against 'experimenting' on live fish or any animal for that matter. Obvoiusly CO2 in high concentration is very harmful to fish and likewise to low and the plants do not benefit.

This is it for now. I have many more questions, but I do not want to sound .

Thanks in advance,
Jesse

[Wasserpest]

Originally Posted by Jesse

I know I can add baking soda to increase the kH and therefore balance the pH, but is there any known way(s) to regulate the CO2 using yeast?

How many CO2 bubbles per minute is suitable for a 10 gal setup?

You don't really add baking soda to balance the pH. If your kH is very low, you increase the buffer capacity of the water to avoid pH crashes, which happen when kH is close to zero.

There are many way to regulate DIY CO2. If the pH dropped from 7.6 to 6.6 you must have a very efficient setup!

You can regulate it by

• adjusting the size of the bottle (2l vs 3l)
• number of bottles
• how much you fill them up
• how much yeast you add initially
• temperature of the area
• way of dissolving CO2
• if using powered reactor, you can turn it off during nights
• surface agitation
• how tight tank is sealed

... Just to name a few. Of course you can't really control it like pressurized CO2 with a monitor and a solenoid.

Therefore, the question of how many bubbles is difficult to answer. You need to monitor the bubble rate to get a feel for how much pH drops with how many bubbles/min in your particular tank.

Originally Posted by Jesse

Fish are sensitive to pH, but are they affected by the relation between CO2 and kH assuming the resulting pH is constant?

If you assume the pH is constant, then CO2 and kH would be constant as well. It's more realistic to consider kH a constant, and changes in CO2 (injection) affecting the pH (dropping). Fish are both affected by pH and CO2 fluctuations, which are related.

[Jesse]

I finally bought a KH test kit by Hagen. Wohoo! The results showed 90ppm. That with my pH at 6.2 equals CO2 at ~56ppm. Good thing I haven't added fish yet.

Most CO2 (pH vs. KH) charts I see have the usual pH units, but are the KH in german degrees? I used the 90ppm*(0.056°/ppm)=5.04°KH to get the reading in german degrees. Is this the correct conversion for alkalinity?

To reduce the efficiency of my CO2 diffuser, I turned up the flow rate of my canister filter. Full speed ahead! This helps to agitate the water surface a little more and causes some of the larger CO2 bubbles to float to the surface. Before the bubbles were trapped in the diffuser and could not escape until they were completely dissolved. I hate to waste CO2, but the system would probably work better on a 20-30 gallon aquarium.

The plants are sure loving it. I had to do some minor trimming last night and moved the larger A. crispus to the back.

Jesse