Rapidly Dropping ph!

[day.t]

Hi, I'm fairly new to this hobby (less than a year) and have already made my share of drastic mistakes. But for the most part things seem to be going swimmingly, at least until a few days ago. We have a 75G tank, fairly heavily planted. I have the plants in various containers for now, with the back floor mostly bare except for smooth pebbles and the front with sand "beaches". Currently this tank has 2 adult platies and a gang of about 20 growing panda corydoras, because we've been using it mostly as a grow-out tank for all the babies from our other tank with the adult pandas. It also has 3 pygmy corys, all that are left from the original 10 we had in a different tank. We moved them to the 75G because they began dying (we still don't know why, but it happened right after we bought them), plus they just didn't seem happy. They almost rejoiced when we put them in with the baby pandas, all of them "frolicking" together.

So, all's been well for several months now. Tests have all been ammonia - zero, nitrites - zero and sorry to say, I quit testing for nitrates b/c I figured if the other 2 are zero every week, why would the nitrates go up? Still not sure on that one, although I am sure I'll get reprimanded for that. I don't always test the ph, either, but that's changed as of yesterday! We've been doing regular water changes, usually about every other week. We take out more water than necessary probably, but it just seems like as long as we're doing it, we might as well get as much new water in as we can.

A few days ago my husband and I both noticed that the corydoras weren't "flying" around like usual and even the platies were subdued and seemed to be hanging out at the bottom of the tank. We weren't sure what to think at that point, but I tested for ammonia, nitrites and nitrates. The 1st two were zero like always, but it did seem like the nitrates were high, about 40 or so (hard to tell with the color chart at times.) We just thought they were being quiet for a while. But the next day when they were still really subdued, I finally tested the GH, KH & PH. The most startling thing was that the PH test was light yellow! We immediately did an 80% water change. I tested again and the PH was at 7. Everyone in the tank seemed to brighten up again. But I was confused as to why the PH would be that low.

This morning they seemed to be active, almost back to normal, except the platies still were hiding a lot and not leaving the bottom of the tank. I've been keeping a sharp eye on them all day and it honestly seemed like they were becoming subdued or lethargic again as the day went on. So... I tested the PH again, and this time it was a very light green, looking to be about 6.4! That's and overnight drop!

What in the world could be causing their water to drop its PH so drastically and so quickly? I removed the driftwood and added some baking soda, and the PH is now about 6.8, almost 7 again. I also added stress coat and melafix because I think everyone is probably pretty badly burned by now. They then got a treat of frozen bloodworms and everyone seems fairly happy again. I just don't want them to be going through this kind of fluctuation all the time, and I myself can become a basket case worrying about it.

Anyone have any ideas besides the usual ones given online? The water quality has never been bad, I don't think it's overstocked (considering the babies are still growing) and I'm just bewildered. Thanks in advance for any advice!

 

[HoldenOn]

Ok so a couple things. Low ammonia and nitrite, yay! However nitrate is actually made when nitrite is consumed by your bacteria. With this in mind it is recommended to do a 50%ish water change every week. I know its a lot of work but it will really pay off in the form of your fish being less stressed and thus not as disease sensitive. Second don't use medications with corydoras, its super bad for them because they are supppeeerrrrr sensitive. Stop dosing melafix right away, another member will know a better replacement solution. My current theory is that you may have stumbled across a piece of wood with pH altering properties. Do you know what kind of wood it is?

 

[mbsqw1d]

Agree that medications are unnecessary here unless fish are obviously unwell. The cleaner the water the better, and the less additives the better, be that medicine, fertilizer, salt...
It might be worth doing a seperate test on your tap water so you know where you stand with regards to PH and even nitrate - some supplies can measure surprisingly high for nitrate. Let your tap water stand for 24 hours before testing as water from the tap contains dissolved co2 which can show a lower PH reading
Lots can affect PH, including nitrates - and so I would guess that this could be the cause here.
Good tank maintenance is performing weekly 60-70% water changes to remove nitrate. And also remove and reset pheromones and allelochemicals released by the fish and plants.
Be mindful not to take water measurements of fresh tap water until a few hours after to avoid false positives. Good to see someone keeping an eye on PH levels! It is surprising to some that our precious filter bacteria colony can be wiped out if it falls too low/raises too high

 

[Byron]

Agree that water changes and only water changes are the best "treatment" in general. Melafix is dangerous to many fish, and it will not do anything beneficial here anyway. Nor will StressCoat unless this is your primary water conditioner to dechlorinate.

The pH is probably easily explained as it is a natural process. We need to know the GH, KH and pH of your tap water alone. And, when testing tap water for pH, you must ensure any dissolved CO2 is out-gassed or the reading will be faulty. If you can get these numbers from the water authority (on their website perhaps), fine. But these are the starting point from whaich "x" will occur.

As organics accumulate, the bacteria primarily in the substrate (not the filter here) break them down and this creates CO2 (and ammonia of course). The CO2 creates carbonic acid, and the pH will naturally lower accordingly. This is a completely natural process that occurs in every aquarium and in nature to some degree; the vastness of the natural watercourse makes this less obvious than in the artificial confines of any aquarium, but it is still normal. But here is where the GH and KH factor in; the higher these are, the more they impact the foregoing, serving as a buffer. Knowing the GH and KH of your source water, and the pH, will give us an idea how this will likely play out. When we talk of a pH crash, it means the buffering capacity of the water parameters has been reached and the pH will suddenly fall. This stage must never be allowed to occur.

I won't get into the complicated issue of adding buffers. If you select fish suited to your tap water GH/pH, you will have no issues. I am suspecting the GH/KH to be low, given the rapid decline in the pH, but let's have the numbers to bee certain. The cories will have no issue with this (it may be something in addition, or it may be your use of the additives plus baking soda all of which impacts them). The liveberarers will not live long in soft acidic water. But again, the safest approach is to know the source water parameters and select fish accordingly.

On thee nitrates, this too is nothing out of the ordinary. Ammonia is taken up by AOB which produce nitrite, nitrite is then taken up by NOB which produce nitrate. This is where the nitrification/denitrification process usually stalls. The anaerobic bacteria that will use nitrate live in the substrate, which is one reason you should always have a good substrate in any aquarium, never bare bottom. Other bacteria use nitrate to produce oxygen, and some of the nitrate converts to nitrogen gas and is released back into the atmosphere. But all of this is usually too slow for the fish load most of us keep in a tank, so we have to help it along by not overcrowding, not overfeeding, keeping the substrate and filter well cleaned, regular (once weekly) substantial (50-70% volume) water changes, and live plants. The plants do not use the nitrate, but their benefit is in using so much of the initial ammonia than there is substantially less nitrite and thus less nitrate down the line.

 

[day.t]

Wow, thank you all three! I'm new to forums, not sure how it works & don't want to leave big long quotes all together, so will respond to each separately. First, HoldenOn, I know what you mean about the nitrates. I was surprised they were that high considering the ammonia and nitrites have been at zero for so long. Like, where are all those nitrates coming from? We don't mind doing water changes. I said we were doing them in that particular tank about every other week, but it's probably more like every 10 days. But hey, every week is good. My husband, (who groaned & frowned when I brought the 1st tank home), is now more enthusiastic (if that's possible) than I am, and I've come home a few times to find he's already done a water change by himself. He dotes on all of the fish, but especially the corys. Funny guy. I was horrified to read about the melafix (saw your post late last night) and was about ready to do a W.C. right then, but they all seemed so perky and happy, so I'm not sure it affected them too badly. Our driftwood is from years of collecting on the Oregon Coast, so I don't know what kind it is. I had two largish pieces that came out last night. There are 2 small pieces with moss on them that I left in for now. Also, there's a coconut shell "bridge" with moss attached. Does coconut effect ph? And there was an oak leaf down there, mainly for the tiniest cory fry, and I took that out just in case. That wood's been in there since we put that aquarium together, but maybe it just took that long for it to leech out (?)

 

[HoldenOn]

Wow, thank you all three! I'm new to forums, not sure how it works & don't want to leave big long quotes all together, so will respond to each separately. First, HoldenOn, I know what you mean about the nitrates. I was surprised they were that high considering the ammonia and nitrites have been at zero for so long. Like, where are all those nitrates coming from? We don't mind doing water changes. I said we were doing them in that particular tank about every other week, but it's probably more like every 10 days. But hey, every week is good. My husband, (who groaned & frowned when I brought the 1st tank home), is now more enthusiastic (if that's possible) than I am, and I've come home a few times to find he's already done a water change by himself. He dotes on all of the fish, but especially the corys. Funny guy. I was horrified to read about the melafix (saw your post late last night) and was about ready to do a W.C. right then, but they all seemed so perky and happy, so I'm not sure it affected them too badly. Our driftwood is from years of collecting on the Oregon Coast, so I don't know why kind it is. I had two largish pieces that came out last night. There are 2 small pieces with moss on them that I left in for now. Also, there's a coconut shell "bridge" with moss attached. Does coconut effect ph? And there was an oak leaf down there, mainly for the tiniest cory fry, and I took that out just in case. That wood's been in there since we put that aquarium together, but maybe it just took that long for it to leech out (?)

Byron gives you the answer on pH I couldn't. Its super informative!
Edit: Bothe the wood and the leaves seem safe. If anyone knows different please let me know

 

[day.t]

mbsqw1d, I tested pH, KH & GH this morning. PH is holding now at 7. KH, oddly (I'm still confused how to read the measurements) took SIX drops to turn yellow while the GH took only between 2 & 3 to turn green. I did test the tap water without waiting, but will test it again later after its sat a while. Oddly, the pH of the tap, which has always been right around 7 before, was so dark blue that I decided to do a high range test on it. It came out as 8.4! I don't get it. But, maybe it'll be lower later today or tonight. The KH and GH seemed to be about the same as the tank. Also, I'll see if I can find our city's water info online. Plus, as you suggested, I'll check the tap nitrates as well. When we do water changes on any of our tanks we usually take it down low, probably at least 75% - 80%, but for that particular tank we may need to do them more often. I'll start keeping a strict eye marking it on the calendar. I had the idea that, because it's such a big tank with not that many fish, it didn't need changed quite as often. But now I'm actually afraid for the residents. We'll change it today mainly to dilute the melafix.

 

[day.t]

Byron, thanks for such an informative message. Like I wrote, I need to let the tap water sit for a while, then will post the results of pH, KH & GH. So, thus far I would definitely say the GH looks low, but not the KH & for the tap water it's certainly not. I just remembered that about 4 days ago I changed out the filter media, just putting new fiber fill in. Do you think that could've been the problem, or part of it? Also I have pre-filter "sponges" on all the filters. Not really sponges, but I use brown "bun-holders" I get from the dollar store. I think they're the same material as the plastic dishwashing scrubbers, but I just don't like the bright colors so much. I have to wash them off every 4 or 5 days because they clog up. I can tell when to rinse them by how the water flow slows down. I always use dechlorinated water to do that.

I'm disturbed at the possibility that the platies might be affected the most. Today the corys are "almost" as playful as usual, but the 2 platies are still staying low and hidden. The male ("BB King") is "special" to me because he's a sky blue color overall, no Micky Mouse, just blues fading to soft greys, and I've never found another like him. We did find the female ("Lucille") a few months ago at - of all places - a petco, in their "miscellaneous" tank - and bought her because her coloring was so close to BB's and I thought they might make more blue platies. So far not, and now I fear losing both of them. Previously Lucille has never been late to dinner, but I haven't seen her out and about or eating for a few days now.

I'm interested in your thoughts on the KH & GH levels.

 

[day.t]

Also, I have an older HOB Penguin 400 filter somebody gave me. It's seemed large enough for that tank, but I could certainly add another HOB or a sponge filter or two. There are two airstones in each back corner, one of them a 2" disc that really puts out the bubbles. The corys always used to play in them a lot before this crash. I could add another airstone more in the center of the tank if you think that might help.

 

[day.t]

I'll at least put that leaf back in if you guys think it won't hurt.

 

[mbsqw1d]

I'll at least put that leaf back in if you guys think it won't hurt.

Yes oak leaves leach very little in the way of tannins, I'd put it back in you want to

 

[Essjay]

Have you looked on your water provider's website to see if they give your hardness? That would confirm (or not) the results from your tester.

GH can be lower than KH. GH just measures calcium, magnesium and trace amounts of other metals. KH measures the amount of carbonate and bicarbonate in the water.

We need to see your 24 hour pH, but it does sound a bit odd that it is higher than it usually is straight from the tap.

 

[day.t]

Hi, essjay and others... glad it's an OK to put the leaf back . We're getting ready to take off, but will check the city's water website when we return. I forgot, duh, that we always have two 5G buckets of water ready to use, and my husband said he'd just filled one of them last night. So I was able to test the tap water after all. The pH was still very high, over 8 (had to use the high range test again, and it came out as 8.2. The KH took only 2 drops to change color and the GH seemed about the same, somewhere between 2 & 3 drops. So, how weird that the KH was so high straight out of the tap compared to aged water, but even weirder that the pH is so high either way! Thank you again for all the great input!

 

[Byron]

The numbers in the last post (#13) are making sense to me. I also gather from "Oregon Coast" comments that you live in western Oregon. You have very soft water, this is the same all through western Oregon, western Washington state, and up into SW BC where I live (Vancouver region).

GH and KH are low. This is ideal for soft water species but hardwater fish like all livebearers will not last long. If you had another tank just for them, you could prepare it to provide harder water, but if you do this in the one tank with the soft water fish, then they will begin to suffer. There is no middle ground when you are dealing with such divergent needs of the fish. Livebearers must have a GH of 10 dGH or higher, with a basic (above 7.0) pH. Must, no exceptions. Soft water fish will be much healthier well below this GH, ideal with you r tap water as is.

So the pH lowering is normal and natural and to be expected, as I explained in my first post in this thread. The high pH is due to substances the water authority add to raise the pH, but these do not affect GH and KH. Vancouver does the same, so I believe does Seattle. In time the pH will tend to lower (as you have seen already in thee tank). Ignore it. You have very soft water, so re-home the livebearers if you can (or set up a distinct tank) and stay with soft water fish, and they will thrive.

Adding organics, like leaves, wood, etc, will also serve to further increase acidity and lower the pH. Again, because the GH/KH are very low and there is no buffering. Fortunately most soft water fish appreciate this too.

 

[StevenF]

I was surprised they were that high considering the ammonia and nitrites have been at zero for so long. Like, where are all those nitrates coming from?

Fish release ammonia and urea into the water. Both onctain nitrogen. Bacteria then consume most of the ammonia and nitrite. After that all that is left in nitrate. There are bacteria that do convert nitrate to nitrogen (which outgassed from the tank and plants do consume nitrate. But in many cases plants and bacteria cannot keep up with the production from fish waiste. Weekly water changes are always necessary even if your nitrate, nitrite, and ammonia are zero.