new to co2, need help

[J.Fisher]

Okay, I just got my preassurized system set up yesterday. The pH I had started with was about 7.6. Upon release of co2 the pH has been dropping slowly and steadily. I am using a pH controller. I intend to only let the pH drop about .2 to .3 per day as I am very concerned about my fish.

Here is were the confusion begins... It was my understanding that when the lights go out I could expect to see a drop in pH. With this in mind I turned off the co2. At that point the pH was about 7.5. I woke up this morning to a pH of about 7.75. I heard one theory that the injection of co2 can sometimes raise KH in turn raising pH. That sounded strange but I checked anyhow . Starting KH: 3, current KH 3. Does anyone have any ideas as to why this is happening?

 

[Aries]

From what I understand (which is minimal) - You turned off CO2 overnight - therfore the water had say 8 hours to get back to non-CO2 parameters - which I would think the standard non-CO2 parameters are 7.75PH. WIthout the CO2 the PH can not drop - I would think.

The same goes for my tank. Turn CO2 on = 7.4PH, TUrn CO2 off = 7.7H. IME, I would test for where the optimum PH level is that makes CO2 where you want it and set your controller to not let PH go below that and enjoy,

HTH a little.

GOod luck

Aries

 

[J.Fisher]

My next assumption would be the more plants I have the less this will be the case. My tank is not heavily planted at all. I will have to moniter things very carefuly as I bring in more plants.

Thanks

 

[reiverix]

I heard one theory that the injection of co2 can sometimes raise KH in turn raising pH.

It would be nice (for me anyways) if injecting CO2 did raise KH. But it doesn't. Your KH is the buffer. The higher it is, the more stable your pH will be. With a KH of 3 you are in the 'just stable enough' zone.

I also turn off CO2 at night using a solenoid on a timer. The CO2 stops injecting just after lights out and comes back on just before the lights. Really though, if you are injecting pressurized CO2 and your lighting is at the high end, then I'd be tempted to max out your tank with plants in one big swoop.

 

[J.Fisher]

At this point I am not comfortable turning off the co2 at night until there are enough plants in there to make a difference. As it is now the pH will rise at night if I turn it off. This is all very new to me so I am watching it like a hawk, don't want anybody to get hurt.

So now that I have co2, what is the best way to buffer the r/o water I will be using for water changes? I figured I would continue to use r/o right. But should I rely on the co2 to bring the pH down as I add new water? The r/o pH being naturaly high seemed to me it would be a shock to the fish (unless it is added really slow I suppose).

 

[djlen]

You are on the edge kH-wise when injecting so you are correct to be very careful.
Pick up some crushed coral at your LFS and a filter bag and put 2 or 3 tbsps. of the coral in the bag and the bag in the filter. Over time this will help stabilize your water.
You can also use baking soda for more immediate affect.
I inject 24/7 with little or no appreciable variation in pH, and my kH is 3.5°H. I would go slowly with changes in bpm until you get a handle on it's affect on your water, especially if you intend to use R/O. I would mix R/O with tap for a while or on a permanent basis if you intend to use R/O, though I don't see the reason for that. Your water sounds fine as it is.

Len