Seachem Reef Buffer PH Issue

[mrbill70]

Hi everyone,

I have been using Reef Buffer to prepare my top off water. I fill up a 5g bucket with RO/DI water for the week. Initially, the water tests as 7.4 PH and 0 dkh. According to the directions, 1 tsp of buffer should raise ph by 0.1 and alk by 0.5 meq/L in 40g of water. So, 1 tsp added to 5 gallons of water should result in a ph increase of 0.8 and alk increase of 4. For some reason, it seems as though my PH is going up much much faster than the alk. I add a teaspoon to the bucket and my ph tests off the chart (goes up to 8.8). The alk is inline as to what it should be.

Because of this, I started reducing the amount of buffer I added to the 5 gallons of water to find the amount that would give me a ph of 8.3. No matter how much buffer I add, even the smallest pinch, it immediately raises the PH off the chart while only registering the slightest alk increase. I'm afraid to use enough of this to get the alk up to where it should be for fear of dramaticially raising my PH.

The instructions on the Reef Buffer say you can't overshoot 8.3, so what gives? Maybe my test kit is so innaccurate (API) that 8.3 is registering as 8.8+?

I also tried diluting the buffered water with unbuffered 7.4 in equal parts and testing that. That still reads 8.8+ when I expected it to at least make it on the chart by diluting it 50%.. I don't know what's going on.

[IslandCrow]

You don't need to add buffer to top-off water. Add it as is. From what I understand, the PH readings you're getting from purified water are inaccurate anyway.

[Randy Holmes-Farley]

Right. Stop adding anything to the top off unless it happens to be a convenient way to add something that you know you want in the tank.

I discuss it here:

Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria
http://reefkeeping.com/issues/2005-05/rhf/index.htm

from it:

http://www.reefkeeping.com/issues/2005-05/rhf/index.php#8

Final Effluent pH

Aside from the issues discussed above concerning the effluent’s pH when the DI resin becomes depleted, the final pH coming out of an RO/DI system should not significantly concern reef aquarists. Many aquarists with low pH problems have asked, for example, if their aquarium’s low pH may be caused by their replacing evaporated water with RO/DI water that they measure to have a pH below 7. In short, the answer is no, this is not a cause of low pH nor is it something to be generally concerned about, for the following reasons:

1. The pH of totally pure water is around 7 (with the exact value depending on temperature). As carbon dioxide from the atmosphere enters the water, the pH drops into the 6’s and even into the 5’s, depending on the amount of CO2. At saturation with the level of CO2 in normal (outside) air, the pH would be about 5.66. Indoor air often has even more CO2, and the pH can drop a bit lower, into the 5’s. Consequently, the pH of highly purified water coming from an RO/DI unit is expected to be in the pH 5-7 range.

2. The pH of highly purified water is not accurately measured by test kits, or by pH meters. There are several different reasons for this, including the fact that highly purified water has very little buffering capacity, so its pH is easily changed. Even the acidity or basicity of a pH test kit’s indicator dye is enough to alter pure water’s measured pH. As for pH meters, the probes themselves do not function well in the very low ionic strength of pure freshwater, and trace impurities on them can swing the pH around quite a bit.

3. The pH of the combination of two solutions does not necessarily reflect the average (not even a weighted average) of their two pH values. The final pH of a mixture may actually not even be between the pH’s of the two solutions when combined. Consequently, adding pH 7 pure water to pH 8.2 seawater may not even result in a pH below 8.2, but rather might be higher than 8.2 (for complex reasons relating to the acidity of bicarbonate in seawater vs. freshwater).

[mrbill70]

Wow, I was wrong on all accounts. I've read multiple times about people doing just the few things you mention: buffering top off water and diluting high ph water to get a measurable reading. Hmm, well im always up to simplifying the routine. Thanks for the article link. I spent some time reading the high ph causes and cures etc., but couldn't piece it together.

[Randy Holmes-Farley]

Do you have a tank pH issue now?

[mrbill70]

I thought I did at first. Yesterday I tested my PH right before the lights went off and it was reading 8.7-8.8 for some reason. In the past I have had ph around 8.1-8.2 to 7.9-8.0 first thing in the morning, which is why I started to buffer the top off. I started going down the list of things that could have caused a super high ph such as the PH of my topoff (your article said either CO2 deficiency or high ph additives are most common causes of high ph). I took maybe half a cup of tank water and blew into it for 2 minutes through a straw. Retesting the water showed the ph down to ~7. I couldn't fathom a CO2 deficiency because my house is newer and well sealed, I run a fan over my sump during the day, and my stand stays closed up.

During all this my lights went off, and because of the confusion I was causing myself with all this, I cleaned out my test kits and took new base readings. The PH in the tank now read 8.3. I tested again 5 mins later and got the same result. For now I'm going to chock it up to some error in testing on my part. It was either that or the ph dropped 0.5 in 15 mins of the lights going off. I still couldn't wrap my mind around the anomaly going on with the buffer in the pure RO/DI water through.

[Randy Holmes-Farley]

FWIW, lighting systems interfere with some pH meters, such as the Pinpoint.

Try measuring on batteries or away from the tank or at least on a different outlet than the lights. :)