would like to lower pH...how?

tf1265

My pH is just a little too high. The water from my tap tests at just above 7.0 - maybe 7.2, but just barely. The water in my tank consistently tests at 7.8-8.0. This is just a bit too high. I have some cories and platies, as well as zebra danios and a betta (several tanks, but same situation with all of them).

Is there anything I can do to keep the pH down a bit? Not a drastic change, but I'd like to keep it around 7.2 for the sake of my fish. My water is on the hard side, not surprisingly. I can't remember the numbers, but I remember the reading was closer to the upper "safe" limit than the middle on the test kit.

I have live plants but am planning to add more. Will this make any difference? I don't add anything to the water except conditioner/fertilizer and don't plan to (i'm not interested in using the commercial pH control products). The conditioner I use is a Jungle brand, and the fertilizer I use is a combined water conditioner also Jungle brand. I've heard drift wood can help with the pH, but I also don't know what to do with it - I've read some things about soaking it and tannins and it sounds very complicated and like it will make my tank cloudy.

They're both 10 gallon tanks, so it doesn't take much to shit the parameters, for good or bad.

pH tap: 7.2
pH tanks: 7.8-8.0
ammonia: 0
nitrites: 0
nitrates: 15 in 1 tank, ~25 in the other (one of them is more heavily stocked)

Thanks!

Byron

First we need to find out why the tank pH is higher than the tap, and there are two possible reasons.

When you tested the tap, did you let the water sit out overnight? Depending upon the amount of dissolved CO2 in the water, it will affect a pH test. Letting a glass of water sit for 24 hours (overnight should be sufficient) and then test will ascertain the more accurate pH, and it may be higher if this method was not used previously.

Second possibility depending upon the above is that something calcareous in the tank is dissolving and raising hardness and pH [the two are closely linked]. This could be rock, gravel or sand made from limestone, dolomite, marble, lavarock, or coral.

Attempts to lower pH often fail because pH is linked to the mineral hardness and a high bicarbonate hardness (KH or Alkalinity) will act as a buffer to maintain the pH where it is out of the tap. You can read more about this in my article:
Water Hardness and pH in the Freshwater Aquarium

That will also contain a brief summary of how to lower pH, but before attempting that, post your answers to the above issues. Also, if you could give me the GH and KH of the tap water (find this out from the water supply folks, many have a website with data posted). All this will tell us what to do. Also, what fish are in the tank?

Briefly to your two questions, yes live plants help stabilize pH but not lower it. And wood will lower pH but minimally, and here again the KH is involved.

Byron.

tf1265

Thanks Byron. I got home very late last night and am at work again at the moment, but I will try to get some answers this evening to post.

tf1265

I looked on my water providers website to see what information is offered. It does include a very detailed chart of any substance that may be in the water in trace amounts and a bunch of regulations and statistics.

I'm not sure exactly what I'm looking for in terms of hardness numbers.

It gives me a pH average of 7.89, which seems awfully high. Range of 6.8-8.8, which seems like a wasted statistic since if it went too much further in either direction that is no longer safe water. I have not yet tested aged tap water, so I don't know where my water specifically falls.

For hardness, it gives me levels of various minerals but no combined number. It gives me calcium hardness as 93 mg/liter. Total dissolved solids number is 153 mg/liter.

Like I said earlier, I know my water is hard, so do these numbers seem to make sense? If not, I'm obviously looking at the wrong thing so what should I be looking for?

Byron

This is making some sense. The pH of 7.8 is close to your tank pH of 7.8 and the likely explanation here is that the tap water is actually around 7.8. As I said, the dissolved CO2 can lower it a lot. When you do the water sitting out overnight pH test I bet it will be close to 7.8.

For hardness, the calcium hardness is critical as GH is largely calcium and magnesium salts. So 93mg/l is roughly 93ppm which equates with 5 dGH which is "soft." Now, we need to see other numbers, can you provide me a link to this data online? I'll check through it. There can be other minerals causing hardness, or the water may indeed be soft.

Higher pH with soft water is quite possible, I have it here, though not 7.8 but 7 to 7.2 with near-zero hardness. It all depends upon what is in the water. And there are other factors. My water all comes from 3 reserviors which happen to have basically identical water. But if yours comes from different sources with different parameters, it might fluctuate depending upon which reservior they use most, or change around depending upon demand, etc.

Byron.