[Byron]

First important thing is to stop adding chemicals to adjust the pH. And no new fish until this is resolved.

The pH in an aquarium is caused by a combination of factors. Some of these will "resist" efforts to alter the pH, resulting in fluctuating pH which is very stressful on many fish and can cause death. Before i explain this, we need some more information, as these factors are related.

What is the pH of your tap water, out of the tap? Run a small jar of water and shake it very vigorously for several minutes before testing. Also, what is the hardness of the tap water? You can find this out from your water supply people, some have websites with water analysis information. It would help to know both the GH (general hardness) and KH (carbonate hardness). If you find their website and have trouble finding this, give us the link and I'll take a look.

To the tank: how long has it been set up? I am assuming it is 10g with originally 5 danio and 2 otos. Are these zebra danio, or something else? And you have live plants, which ones and how many? A photo of the tank would answer this last question best, if you can attach one.

What water conditioner do you use? How often do you do a partial water change, and how much water is changed? Are there any other chemicals or substances going in the tank aside from the conditioner and the pH adjuster?

Please give me all the above info and I'll continue.

 

[Byron]

Thank you for this information. Now I can explain exactly what's happening, since what you provided makes sense. This may be a bit long, but it is important to understand what occurs in an aquarium, and as you have seen, things can occur quickly to the detriment of the fish.

The pH is the measurement of the ratio between two ions, the positively-charged hydrogen ion and the negatively-charged hydroxyl ion. Acidic water has more hydrogen ions, alkaline water more hydroxol ions. Neutral water is pH 7, acidic is lower and alkaline higher on this scale.

Fish, plants and bacteria release CO2 (carbon dioxide) continually; more comes from various bacteria than the fish and plants. CO2 produces carbonic acid, and this causes the pH [which is the measure of how acidic or alkaline water is] to lower. As organics [fish waste, uneaten food, animal and plant debris, bacteria dying, etc] increase, more CO2 is released and thus more carbonic acid. It is non-stop.

The pH is loosely connected to the water hardness. Hardness is the measurement of mineral salts in the water, primarily calcium and magnesium, but others also impact hardness. Carbonate hardness (expressed as KH] is the amount of bicarbonates in the water and these act as a buffer to pH. It does this by reducing fluctuations in hydrogen ions, thus preventing the pH from lowering. But at some point the buffering capacity may be reached, and then the pH can suddenly fall, what we term a pH crash.

According to the info you have provided, your water has zero KH, which means no buffering at all. The aquarium will therefore naturally become more and more acidic, and the pH will lower. This will be steady, but not sudden, and depending upon the fish species they usually adjust. In your case, having mainly soft water fish, they are generally OK with acidic water. But it can get too acidic.

We prevent this a couple of ways. One is regular water changes. The more water changed and the more often, the more stable the pH will remain. Provided something else doesn't impact it, such as overcrowding which increases the organics beyond what this can handle.

Plants also work to keep the water stable. They do this through their diurnal cycle. In a relatively-heavily planted tank, the pH will be higher at the end of the daylight period and lowest at the end of the darkness period. I wrote at length about this in another thread, and won't repeat all that here, but you can read it if you're interested in the process; it is post #22 in this thread:
http://www.tropicalfishkeeping.com/freshwater-aquarium/ph-levels-pretty-high-68972/

The pH adjusting chemical you were using clearly was inadequate to keep up with the increasing CO2. Normally these adjusters work fairly well when the KH is non-existent, but even if it did, I would not continue to use chemicals. The fluctuating pH is highly stressful, and other side effects from the chemicals can be even worse. My thinking is always to put as little stuff in an aquarium as possible, and let nature do the work which will always be safer and less expensive.

On the plants, those are actually terrestrial plants, not aquatic. That explains their minimal impact on all this. True aquatic plants would use most of the CO2 and help prevent lowering pH. And, those plants will start to rot and cause even more acid. I would remove them and replace them with true aquarium plants. Many of the commonly-available species are included in our fish and plant profile section [second tab from the left in the blue bar across the top of the page]. Have a look, and ask any questions and one of us will be able to answer about the plants. At this stage, I would recommend fast-growing plants like stem plants because they use a lot of nutrients including CO2 from the water.

The bubbles from the rock was merely air escaping; rock is sometimes very porous. Not an issue there.

Please stop using the Waste Control. This is only making things worse, and it speeds up the decomposition of the organics adding yet more CO2. It also releases ammonia, although this is somewhat harmless since in acidic water ammonia changes to ammonium. I won't go further into that.

The water conditioner is sufficient, with each water change, enough for the replacement water volume. Plant food is fine, but as I say you need some true aquatic plants. StressCoat I would also stop, this is just another chemical mix going into the soup, and it is not needed.

I would increase your water changes to 30% and one every 3 days for a week or so to slowly stabilize the tank. This will be slow enough to not harm the fish.

Byron.

 

[Byron]

I'm glad you asked about the plants then. I had no idea these were not aquarium plants. That might explain why I could never get them to grow more than they were when I bought them, they just sit there and eventually die. I will get some new plants asap. Until then I will remove all but the newest plants, I don't want to stress the fish by suddenly having no plants at all.

What do you mean by stem plants? Don't all plants have stems? Or do you mean the kinds of thick plants I see in pet store aquariums that are like bamboo?

I will stop doing extra chemicals and start doing more water changes like you suggest. Thanks for all your help.

You're very welcome. Keep us posted on developments. Just go slow with the water changes.

Stem plants are plants like Brazilian Pennywort, Wisteria, Cabomba, Bacopa, and many others. They are under the "Stem Plants" section in the profiles. These plants simply grow a continuous stem from which roots and leaves emerge. You can break them at any point and create new plants with bits of the stem. They can be planted in the substrate (gravel) or allowed to float sometimes. What we call substrate-rooted plants are those like the ones you have, that have a crown from which leaves arise upward and roots downward, to put it simply. Sword plants are good substrate-rooted plants, you should consider some of those in time.

 

[Byron]

Yes, those along the front are a stem plant, though I'm not exactloy sure which one. It bears a very close resemblance to Nesaea crassicaulis, but may more likely (considering the store source) be Bacopa caroliniana. Anyway, planting it apart like that is good at this stage, as the light will be better for the lower leaves, not that there are many. But they should recover.

You're in Philadelphia, are there no fish stores other than the chains in that city?

 

[Byron]

There are I'm sure, I just don't really know of them! The other pet store I know around here is called Monster Pets, which is pricier but has lots of exotic fish (barracudas, piranhas, electric eels, pufferfish, wolf fish, and my favorite red-tailed catfish, of which I hope they warn people about their adult size!). Unfortunately they do not have any live plants.


I'm glad that the plants I got are indeed stem plants. And I think you said that with stem plants you can just cut off part of it and that part will grow on its own? Already you can see that one of them is too tall, so I would like to cut that one down. I tried to look online of what the plants might be, my only guess was moneywort for the tall ones and some kind of anubias for the ones with big heart-shaped leaves, but your guess is better than mine.

I missed the heart-shape leaf plants. Frankly, I'm not sure about those, they may well be non-aquatic.

If you trim the stem plants, you cut them so that the top portion which is the growing tip becomes the new plant, thereby removing the lower portion. Stick the top portion in the gravel, it will root and grow. Depending upon how fast stem plants grow, they need regular trimming to keep them below the surface. No problem if they grow along the surface, but when they do this, most will lose lower leaves and you're left with bare stalks in the aquarium.

Finding a reliable "fish" store is worth it.