Treating RO water for topoff

[stoneroller]

I don't have an auto topoff so I get a pitcher from the RO faucet. I had been just going straight but now I am figuring out that I should probably treat that RO water. Lately I have been using Reef Buffer since my pH = 7.8. On some days, I use Reef Builder.

Good strategy? Recommendations?

[discuspro]

Are you talking about your aquarium pH being 7.8? If so what time are you reading it? You should also test your alkalinity. If you don't have a test yet I would recommend getting one because that can help pH adjustments.

I use RO/DI with no buffer in the RO/DI water and my tank is around 8.13 during the day.

[stoneroller]

In the morning before I run it up to the LFS! test kit obtained this weekend but haven't used it yet, I will when the kids go to bed, lol

[discuspro]

Okay, if you are taking water in the morning either before the lights go on or shortly after they turn on then a pH of 7.8 wouldn't be too bad. Mine normally gets around 7.9-8.0 at night until the lights are on for an hour or two, then it goes back up.

[stoneroller]

I broke out the test kit this afternoon after the halide had kicked in for a couple of hours.

pH close to 8.0 (Jungle Lab)
Salinity = 1.026 using a swingarm (value adjusted based on recent LFS tests)
Calcium = 500 (a little higher than recent LFS values) (API Master Reef Kit)
dKH 10 (API)
phosphates 0-0.25 (API)
nitrates 5-10 (API)

pH and KH a little low?

[discuspro]

dKH sounds good, if it was me I wouldn't go any higher. pH is okay. What increments does your pH test use?

[caferacermike]

I'd say your PH was only ok, not great, for a fish only. For a reef I'd try to get it around 8.2-3. This can be done with water changes and or added buffers.

[stoneroller]

What increments does your pH test use?

0.2 pitiful increments


I'd like to get it up there, I'm using SeaChem Reef Buffer (2 tsps in my daily RO topoff water for a 72 gal). I figure it's best to take it slow, right?

[matt]

Ph will vary considerably throughout the day. If your carbonate hardness is dkh 10, which is higher than NSW levels, the only reason your ph can be low is due to higher than normal levels of carbon dioxide dissolved in the water as carbonic acid. There are no other causes. The source of the carbonic acid could be from animals' biological activity or from CO2 in the room air where your tank is, or from a calcium reactor. The easiest and fastest way to raise your ph would be to drip some KW.

Adding more buffer won't do the job. If your buffer is sodium carbonate it will temporarily raise ph but it won't neutralize the dissolved CO2. Since you asked about treating top-off water, the best thing would be to get some KW powder and mix it in with your top-off water, then add it slowly (drip is best) to your sump.

8.0 is not particularly low in the morning; plus your ph test kit might not be really accurate, and it's winter, which means we have our windows closed and residual CO2 in houses is really common. If you have a skimmer and can hook up the air intake to an outside source, your ph might go up. I wouldn't worry about it too much.

[stoneroller]

pH will vary considerably... how much of a swing? 0.5 units? and would you see larger swings in smaller tanks?

Thanks so much for all the responses. Ya've been very helpful.