pH Falling?

[An t-iasg]

Hi everyone,
You may remember that I've started a [acronym:3e6cb2bd62="Do it yourself"]DIY[/acronym:3e6cb2bd62] [acronym:3e6cb2bd62="Carbon dioxide"]CO2[/acronym:3e6cb2bd62] system. I've used the Hagen cannisters and the Red Sea diffusers. I've had a lot of trouble with the Red Sea diffusers. One is fine and the other one wasn't. I've sent back two diffusers already, and although one of them is fine, I'm not buying another one for the OTHER tank.

So in the tank without the Red Sea, I'm trying something different. I recently put in a Marineland bubble wand, which gave me a nice [acronym:3e6cb2bd62="Carbon dioxide"]CO2[/acronym:3e6cb2bd62] level of 15 [acronym:3e6cb2bd62="Parts per Million"]ppm[/acronym:3e6cb2bd62], the same as the Red Sea when it worked. At the hatchery, I saw a Kordon Mist-Air fine airstone, and bought it. It has one small, steady stream of bubbles that are disappearing before they hit the surface. I did a routine pH check the other day and my pH is 6.4, [acronym:3e6cb2bd62="Carbonate Hardness"]KH[/acronym:3e6cb2bd62] is 2, for a [acronym:3e6cb2bd62="Carbon dioxide"]CO2[/acronym:3e6cb2bd62] level of 24 [acronym:3e6cb2bd62="Parts per Million"]ppm[/acronym:3e6cb2bd62].

I'm a little concerned, although according to the charts, I'm still at a safe [acronym:3e6cb2bd62="Carbon dioxide"]CO2[/acronym:3e6cb2bd62] [acronym:3e6cb2bd62="Parts per Million"]ppm[/acronym:3e6cb2bd62] level for the fish. The fish looks fine, but I don't know why the pH would fall if the [acronym:3e6cb2bd62="Carbonate Hardness"]KH[/acronym:3e6cb2bd62] is the same. My [acronym:3e6cb2bd62="Carbonate Hardness"]KH[/acronym:3e6cb2bd62] has always been 2. The new airstone doesn't look like it's putting out that much [acronym:3e6cb2bd62="Carbon dioxide"]CO2[/acronym:3e6cb2bd62]. This yeast mixture is 2 1/2 weeks old. At a pH of below 6.5, some of the nitrifying bacteria may die, right?

I did have some red wendtii crypts melt to the gravel. The petchii are fine. I removed the wendtii leaves. Maybe I should feel under the gravel for the rhizome. Maybe it's rotting too. I'm just trying to determine what is making the pH fall, and what should be done about it. Ideas?

This pH level of 6.4 has stayed steady for about 24 hours. Nitrates are 10 [acronym:3e6cb2bd62="Parts per Million"]ppm[/acronym:3e6cb2bd62] and phosphate is 1 [acronym:3e6cb2bd62="Parts per Million"]ppm[/acronym:3e6cb2bd62].

(Also, the ambulia doesn't need to be encouraged THAT much - a higher [acronym:3e6cb2bd62="Carbon dioxide"]CO2[/acronym:3e6cb2bd62] level - in a small tank! )

[Hoovercat]

Your [acronym:41203d7609="Carbonate Hardness"]KH[/acronym:41203d7609] shouldn't change from injecting [acronym:41203d7609="Carbon dioxide"]CO2[/acronym:41203d7609], only your pH. If the buffer is weak it will drop slowly though which is one of the main reasons to stay vigilant with water changes. I haven't heard of nitrifying bacteria dying off below 6.5 so maybe someone else will chime in on that. Personally, I wouldn't disturb the melted crypt as it's chances of recovery are much better if left alone.

[An t-iasg]

Thanks, Hoovercat. I do 50% water changes every week. My pH has been 6.6 with a [acronym:f4fc376c16="Carbonate Hardness"]KH[/acronym:f4fc376c16] of 2 for almost 6 weeks or so now. (Before adding [acronym:f4fc376c16="Carbon dioxide"]CO2[/acronym:f4fc376c16], it was 7.2-7.4.) Now it suddenly, or so it seems, it falls to 6.4 with the same [acronym:f4fc376c16="Carbonate Hardness"]KH[/acronym:f4fc376c16] of 2. Since it's only a 5 gallon tank, maybe I'll have to do water changes twice a week - the 50% change and then a smaller one mid-week. Hmmm. Three planted tanks, even though they are 5 gallons, are a lot of work!

[malkore]

Everything is normal.

Your new airstone is creating smaller, more easily dissolved [acronym:69bcf38ddb="Carbon dioxide"]CO2[/acronym:69bcf38ddb] bubbles. Because of the increase in efficiency, you're getting more [acronym:69bcf38ddb="Carbon dioxide"]CO2[/acronym:69bcf38ddb] into the water, thus a lower pH.

No need to do extra water changes. The [acronym:69bcf38ddb="Carbon dioxide"]CO2[/acronym:69bcf38ddb] isn't going ot keep building up...its just hit a new peak with the new airstone.

Also, 30ppm is about the maximum [acronym:69bcf38ddb="Carbon dioxide"]CO2[/acronym:69bcf38ddb] level that benefits plants. [acronym:69bcf38ddb="Carbon dioxide"]CO2[/acronym:69bcf38ddb] doesnt' displace [acronym:69bcf38ddb="Oxygen"]O2[/acronym:69bcf38ddb] in the water, so even with levels at, say, 100ppm, you could still very much have full [acronym:69bcf38ddb="Oxygen"]O2[/acronym:69bcf38ddb] saturation, and happy fish (of course your pH would be like, 5.4 so that'd be hard on the fish). My point being, if your [acronym:69bcf38ddb="Do it yourself"]DIY[/acronym:69bcf38ddb] hits 40ppm but stays stable...great. The fish won't mind, the plants won't mind, and in fact it may drive off nusiance algae better.

[An t-iasg]

Thanks for the reassurance, Malkore!

I had wondered about that a few hours ago and logged on to post a "what do you think of my new airstone causing it" question, because it's the only thing that changed. It must have such fine microbubbles that they can't be seen very easily.

I know fish are not harmed by the pH swings as influenced by [acronym:8443de826a="Carbon dioxide"]CO2[/acronym:8443de826a]. But I did pull the airstone last night. This morning the pH is 7 (if the pH didn't rise that would mean some really weird water chemistry!) I will do my water change today instead of tomorrow (the water is aged already) and put the stone back in. It's good to know that the [acronym:8443de826a="Carbon dioxide"]CO2[/acronym:8443de826a] saturation reached its peak and I don't need to do an extra water change during the week. The only drawback is that this ambulia does NOT need any more encouragement! I'm pruning it twice a week as it is!

PS. One crypt has one new leaf. The other crypt's tuber is a slimy mess. I picked off some of the slimy stuff and re-inserted it with a new root tab.