Slow PH Drop

Flame · 10-09-2005, 03:56 PM

Before RO/DI PH 8.3 - 8.4
After PH Now 8.0 (Over 2 weeks and 2 water changes 1 gallon a day top off)

Ok I have noticed a slow drop in my PH since I started using the RO/DI unit. I test the water from the unit and got a PH of 7.2. Would I need to add backing soda or some other buffer to the water before I top off. I did test and found the 2 table spoons brought the PH up to 8.4. I do not think its an CO2 issue my house is not that tight and we have the windows open a lot. Any help or suggestion would be appreciated.

Thanks in advance

tdwyatt · 10-09-2005, 05:14 PM

Quote:

Originally Posted by Flame

...noticed a slow drop in my PH since I started using the RO/DI unit.

I test the water from the unit and got a PH of 7.2. Would I need to add backing soda or some other buffer to the water before I top off?

No, your pH in the RO/DI will vary a bit based on what cations/anions make it through your RO membrane that the DI resin cart must exchange ions for. Regardless, unless your RO membrane is shot, your pH of the effluent should be near 7.0 (remember, plain water should have equal numbers of dissociated ions, both hydroxyl and protons). Before making any drastic changes to your tank, make sure that your testing for the pH values is correct.

How DO you test your pH? How often? What time of day? and how do you supplement your calcium and alkalinity now? What are the values for your salinity, average temp, pH, calcium, magnesium, and alkalinity? Knowing each of these parameters is necessary to determine where you are in the big picture for your pH.

Flame · 10-09-2005, 05:32 PM

Temp= 78F
Salinity= 1.023-1.024 (Refractometer)
Alkalinity= 10
Calcium= 400
PH is 8 early morinings before lights come on
Calcium is added a 1/4 teaspoon of Kent Calcium Daily
Do not test Magnesium

Loverotties · 10-09-2005, 06:09 PM

Ph will be the lowest in the morning and highest when the lights are going off at night,unless you have a light on fuge and then it more stable.

Flame · 10-09-2005, 06:16 PM

Quote:

Originally Posted by Loverotties

Ph will be the lowest in the morning and highest when the lights are going off at night,unless you have a light on fuge and then it more stable.

Just tested the PH and it is 8.0 right now. I do not see much change through the day.

Thanks

tdwyatt · 10-09-2005, 10:19 PM

Quote:

Originally Posted by Flame

Temp= 78F

Salinity= 1.023-1.024 (Refractometer)
Alkalinity= 10
Calcium= 400
PH is 8 early morinings before lights come on
Calcium is added a 1/4 teaspoon of Kent Calcium Daily
Do not test Magnesium

test with a salifert kit for Mg please, how do you test/determine your pH? What is in your tank in terms of creatures that use Calcium and alk?

Now I'm curious, because by just adding Ca alone, you deplete alkalinity from the water column unless you're nowhere near supersaturation (strike that, at 400 PPM Ca++ and AQlk at 10 dKH you're there) or you have a constant source of reactants or supplements to provide the alk. Unl;ess your system has some source of CO2 to drive your pH down all day, I am suspect of your measuring method for the pH, as with any photosynthesis going on, the pH will gradually rise during the day to around 8.4 on its own as CO2 is used up by the zooxanthellae or by algal chloroplasts. You mentioned adding bicarb and having it increase your pH to 8.4 (must have been tested just after the qddition...), are you doing this on a regular basis? If you are using a CO2 driven Ca reacor, I would think that it is not quite adjusted right, but I don't see any mention of such a device for your supplements.

Is your home air conditioned?

Flame · 10-10-2005, 05:22 AM

Yes I am adding CA alone. (Kent concentrate liquid calcium) No other additives. The only thing I have using calcium and alk is on medium torch coral, and coarlline. Livestock is 15 snails and 4 red leg hermit crabs. House does have AC, but it is an old home not real tight. The PH issue just started after I started using the RO/DI unit and not buying DI water. I think I need to find another way to test PH I am using the Saltmaster test kit. I have not added bicarb yet just looking at this as a poosible answer.

tdwyatt · 10-12-2005, 01:09 PM

change your testing kit to either Salifert (OK, but best of the chemical kits) or get a PinPoint meter (highly recommended) and run it 24/7 in a lightleses part of your tank (the sump) and use the battery for power, esp if you have electronic heaters, ballasts, or nearby electronic equipment, as the probe wire will p/u RF from these devices and skew results. Don't make any changes to the system until you can get some reliable results from your testing; the kit you mentioned is notorious for skewed results, and I suspect this is the source of your reading issues.

Let's get the testing errors reduced first, then if there are STILL pH-reated issues, we can tackle them at that point.

lemmeno where you are in a few days.

Flame · 10-12-2005, 01:14 PM

Ok thanks a lot to all that is helping with this issue.