pH drama

[Regen311]

I have two tanks, a 55 gallon well established and a 10 gallon fry tank, set up about 2 weeks in an emergency for cory fry. The tapwater in my area comes out off the charts as far as pH goes (9) but after it sits it goes down to 6.6, which is the pH my main tank is at. The nitrates, nitrites, ammonia all stay very near 0 in the 55 gallon. In the ten gallon, I've had issues with ammonia, due to the emergency set up, that I have under control with seed material and plants from the 55 gallon. I did a pH test today however, and it was too low to even register. It looked lighter than the 6.0 pH. I use the aquarium pharmaceuticals master test kit. What could cause the tank to have such a low pH? I'm freaked out. I have some zeolite in there due to the ammonia issue, and a sponge filter, but that's it. There are no meds in the tank, and I've been doing 50% water changes daily using stresscoat. I haven't done a water change since Wednesday morning however because the ammonia finally stabalized. Any ideas?

[Purrbox]

Based on the way that your pH fluctuates from the tap, I'm guessing that there is probably very little KH in your water. The KH is what stabilizes the pH. I would recommend testing your tap water to determine the KH, which will give a better idea of how to proceed.

[Regen311]

I had kH test strips, it was a multi dip strip I used a few months ago, and it indicated that the water is very hard. It was almost to the maximum that kh would measure. The water is unusually high coming out of the tap, I'm not sure why it settles to what it does, but in the big tank, the pH is exactly the same as water that has set out for a little while (I got water out of a pitcher in the refrigerator to test tonight, because I didn't have time to set some water out for a while too test. So, probably a day old). The area around here though, the water is very hard, in general. I'm just confused over the whole thing because the small tank has basically the same things the large tank does. I've never really looked too much at pH because it hasn't been an issue. I was just alarmed that the fry tank had such a low pH and was wondering if there was anything I had done inadvertently perhaps to cause it.

[rkilling1]

Hard water and high buffering capacity are not the same thing. Having a high GH is what is considered hard water. Having a high KH is considered to have a high buffering capacity. IE you could have a high GH, but have a low KH.

[Regen311]

Well, I'm getting another test kit tonight after work to check the kh and all of that, but I'm still not sure why it would drop like that in one tank and not the other. I don't like the idea of not fixing the underlying problem.... that low of a pH scares me. It was not even readable on the pH scale. It was the lightest color there is, and it seemed lighter than that.

[Purrbox]

That's why we need to figure out what the KH really is now, both in your tap and your aquarium. Tap water can change over time as many water treatment plants treat the water differently at different times of the year. They also may decide to switch treatment routines to provide better quality drinking water. If a low KH is the culprit there are some easier and safe ways to add some KH back in.

[Regen311]

Well. I tried doing a GH and KH test. The GH test worked, it's 7. But the KH test didn't. When I added the drops of the indicator solution, the water never changed color at all. Not even to the starting color. It says that if it immediately changes to the "end" color, then it's very low, but the water color never changed at all. After 10 drops, the water was still clear. The GH test worked, so I'm assuming I'm doing the test right... I'm going to try to see if I can get a KH test kit somewhere, but I've really only seen the master kits at pet stores around here, and that's like 20 dollars, and I already have the master test kit, the KH test just isn't working... I'm trying to figure out what to do...

[Purrbox]

You could take a water sample into the LFS and ask them to test the KH. This will get you an immediate answer and help to determine if your test kit is bad.

[marchmaxima]

Originally Posted by Regen311

When I added the drops of the indicator solution, the water never changed color at all. Not even to the starting color.

That's what happened to me the first time I tested KH (and every time since)... I have no buffering capability whatsoever in my water and it also didn't help that I have low GH too.

If your KH is that low, it will go straight to the end colour.

[Regen311]

But it didn't go to the end color. It didn't change color at all.

[marchmaxima]

what colour was it supposed to start and end at? what colour was yours?

[rkilling1]

When my KH test didn't give me an endpoint, it was too old to use anymore. After purchasing a new one, it worked just fine. My test kit was just over a year old.

[Regen311]

I'm pretty sure it was just too old to use. I think the start point was like blue and the endpoint orange, but it never changed from clear. In any case, I took the water to the local LFS today. As it turns out, the kH is almost 0. It was the second to lowest color on the dip strip (I didn't write down the numbers... he was kind of in a hurry and I didn't have a chance to, I just saw that it was about as low as it can possibly go) and the gH was the second from the highest it could go. Nice combo there So I guess that's the answer, my water has no buffering capacity. The 6.6 pH in the big tank is fine, that seems stable.... but the little tank... I don't know. The babies don't seem to be suffering and their sub-6 pH, but I still don't know what caused the drop or how to fix it...

[marchmaxima]

Sounds identical to my water... I've had no issues... then again, I'm not attempting to breed or anything like that.

[Regen311]

Right well, I've had no issues either in the large tank. The concern i have is how low the pH is in the baby tank, and then introducing them into the larger tank with the pH being so high, and I also would like to know what could have caused the pH to be so low in that tank. That's the only thing that worries me. I generally am not concerned with pH at all, as it is usually not a problem as long as it isn't fluctuating. I'm not really trying to breed or do anything fancy. I just don't like there being a water issue like that and not having any clue what caused it Curious by nature I suppose.

[jsoong]

What is causing pH drop is fish waste (& decomposing matter).

Ammonia (NH4+) turns to nitrate (NO3--) by exchanging the H+ for O--. Excess hydrogen ion = acid.

Any change in water chemistry is more pronounced in a small tank - less water to dilute things out, plus less absolute amount of buffer.

With your high GH, it is possible that you have a second (non-carbonate, hence not detectable with the KH test) buffer in the water. At a certain critical concentration ratio of the 2 buffers, the pH can suddenly swing from the equilibrium pH of the first buffer to that of the second buffer with a relatively minor change in the concentration ratio.

In practical terms, if you have low absolute buffering capacity, you can maintain pH stability by adding buffer, or simply doing more water changes to replenish the buffer. If you have a 2 buffer system, the thing to do is to increase one of the buffer's concentration to bring the ratio out of the critical range.

The first thing to try in your case is to increase the amount of water change (removes waste & replenish the buffers) to see if you can bring the small tank's pH & stability closer to that of the big tank.

[Purrbox]

I could be that the substrate in the larger aquarium is buffering the water ever so slightly, or as jsoong mentioned the excess waste from feeding the fry is creating enough waste to knock out what little buffering is there.

I'd probably look at adding a small amount of Crushed Coral to your filter. This will help to buffer the water without having to remember to add an additive for buffering with each water change. If you want a little more control you could look at adding Baking Soda to buffer the water. With either method you'll want to adjust slowly so as not to shock your fry.

[Regen311]

Awesome Thanks so much. So again it's just an ammonia/cycling issue. It's been so long since I've dealt with all of this. My first aquarium was a fully stocked 10 gallon I bought all at once, then came on here and found out how horribly wrong I'd done it all. That was 4 years ago I think? I guess I forgot how much of a pain it is dealing with an uncycled tank. And now I even have the seed material from the large tank, I did it before without anything... crazy... oh well, the fry are a nice surprise so the work it's taking is well worth it Thank you all.