Crushed Coral Gone Bad?

[anamb95]

Hi, all! I'm a new user on the forum, and I joined because I am not able to figure out what's going on with my tank. I was hoping someone could help me with this. (Bear with me; there's quite a story to this.)

A little bit of background: I have been keeping fish for 12 years now. I have a 20H freshwater aquarium that was replaced because my old one sprang a leak. It used to be a community tank with cories, snails, and a betta. However, right as the leak happened, all of my cories and snails died within days of one another. The leak was very slow, so they hadn't been transferred to the new tank yet. The only surviving fish, miraculously, was my betta. I replaced the tank and put some new substrate (old substrate was ~3 years old by that point), but kept all the old filter media and decorations to preserve bacteria. The only new additive was the substrate. The new tank has a sponge filter, an oversized HOB filter, and sponges everywhere to facilitate bacterial growth.

I believe the old tank developed old tank syndrome from old and compacted substrate, because the pH was scary low (it didn't even register on the test kit) and ammonia was around 4.0 ppm. My betta, somehow, still hung in there. Unfortunately (but expectedly), the low pH and high ammonia transferred to the new tank. After months of a painstakingly slow cycle and lots of water changes that made our rose bushes very happy, the ammonia level finally dropped to zero (no higher than 0.25 ppm) and stayed that way. I was able to scale water changes back to every other week (what I found works best with that tank) and parameters always read normal. However, the pH was still very low, despite normal parameters everywhere else (ammonia, nitrate, nitrite, etc.). As a result, my aquarium plants basically all died off and any left were melting and/or covered in algae. This, of course, caused the ammonia to rise a little bit.

To help with this, I bought crushed coral to raise the pH, as I heard it was a safe and natural remedy for low pH. (I installed a small HOB filter with an extra sponge for bacteria to use for the coral.) Right as I started this, my ammonia was at 0 ppm. I watched the water cloud up, so I assumed it was doing its work. Plants were also immediately doing better. I did a test the other day before my regular water change to see where things were at, and the pH was at a nice 7.4 ppm. The ammonia, however, was completely maxed out (8.0 ppm+). What I thought was clouding from the coral was actually a dangerous ammonia spike. I couldn't detect it because I also have Indian almond leaves in the tank, which turn the water orange due to the tannins (same color as ammonia clouding). My betta was also perfectly happy and energetic and the clouding actually went away on its own before the water change, so I never knew anything was amiss.

I immediately did a large water change, but the ammonia has been steadily climbing ever since. I will continue to do water changes to drive the ammonia level down. Does anyone know what's going on here? Did I just undo my previous cycle on this tank? From what I understand, it would seem to be ammonium-to-ammonia conversion from the higher pH, but I want to be sure. I also ask because, in all my years of keeping fish, I have never dealt with this before. For the record, my betta is somehow still hanging in there, doing his little happy-dances, exploring his tank, and swimming around like a happy camper...

Sorry for the novel, but any advice here would be greatly appreciated. Thank you all!

Edited June 21 by anamb95

[Cory]

Are you sure you actually have ammonia? Could you be getting a false result? Doesn't make sense to have a stable tank turn into a non stable tank once you add crushed coral. Fish also looks to be doing fine. If you really had 8.0 ammonia, all fish should be dead. Getting a local fish store to test it to confirm could help.  Also some dechlorinators give false ammonia results to some liquid test kits.

[anamb95]

Hey, Cory! Thanks for your reply. The API test kit shows ammonia, and the water is also foaming. But you're right; it could be a false positive. My betta has his fins completely fanned open (no clamping) and he's very active. I just don't know what would cause the false positive, as I only added the crushed coral. I started adding Prime to the water, but that was only after the water change and after I did the test.

Edited June 21 by anamb95

[daggaz]

If itcreally is high ammonia, you should get your betta out until you figure it all out.  He might be ok for a while, but ammonia burns his gills and eventually he will die of suffocation. 

[anamb95]

Hey there! Thanks for your reply.

Yeah, you're right about that. I'm doing large water changes (50%+) to drive the ammonia level down (I have only done one so far and will do another today), but if the ammonia outpaces the water changes, I will move my betta to my spare 10-gallon.

[johnnyxxl]

I did some research and the general consensus is possible that it's used error for the test.  I am not sure if that's what you wanted to hear. 

I would wonder did you rinse the coral before you added it?

[Cory]

This kind of stuff is frequent. You made a change and then notice something therefore it must be that. But in reality it's just as likely to not be it. You can google and see that prime has problems with api ammonia liquid kits. Also if you didn't rinse or rinse well enough on the crushed coral, it causes cloudy water and foam at the top. Anyone who has ever just dumped in a bag, going, I'll just water change has seen the foam it can cause.

That being said, it could be something else entirely. But if I had to bet, I'd guess it was the situation described above as 8ppm ammonia your betta shouldn't be loving life and crushed coral shouldn't have that reaction either.

[anamb95]

Hey, Johnny! Thanks for your reply. I did two separate ammonia tests before the first water change, and they showed the same result. I also took another test after the first water change and it still showed elevated ammonia (at ~4.0 ppm). I'm going to do another test today before the second water change and again tomorrow. As for the coral, I did rinse it as per the instructions, but it's possible I didn't do a good enough job. That's why I thought the cloudy water was from the coral, which it definitely could have been.

[anamb95]

Thanks, Cory! I guess I wasn't so sure because the Prime never seemed to mess with the API kit before. For example, when I was establishing the new tank (before adding the coral), I would add Prime to bind any excess ammonia, and the tests would always show between ~2.0--0.25 ppm; and then I stopped using the Prime once the ppm hit zero. So the massive jump to 8.0 ppm in the span of two weeks was shocking, especially given I hadn't used Prime in several weeks and the pH had also increased at the same time. But I understand what you're saying and I trust your expertise. I might also purchase another test kit, as this one could be expired. It technically says it expires in July of 2025, but I received it all the way back in 2020. I will also take your advice on getting the water tested at the pet store. If it is confirmed to have high ammonia, my fish may have hit the genetic jackpot.

[anamb95]

Quick update: just got home from work and could do a quick test of everything before hopping on the water change. Here is a photo of the tank setup (detritus is dead algae from last water change; there is still algae present from previous low-pH situation), a photo of my betta, and the test results (API liquid and Aquarium Co-op test strips). There is a notable difference between the test strips and the liquid kit, which leads me to believe my liquid kit is out of whack. This was happening before I added Prime (with the initial maxed out ammonia reading), so my test kit might be expired. Water smells fine; no immediate odors are present. A very strange situation this is for sure, but I will take a sample of the water to get it tested from a local fish store to get a final consensus.

Edit: betta's name is Miso.

Edited June 21 by anamb95

[Rube_Goldfish]

You could also test the test by measuring distilled water, if you've got it (or get some from the grocery store), since it's a known quantity. If it shows ammonia, you'll know that something is wrong with the test itself.

Edited to add: Miso is a handsome fella!

[anamb95]

You're absolutely right, I can do that also. I have plenty I use for my plants, so I can spare some. Thanks! 🙂

[Gastroplod]

I recently had the same issue with aragonite sand (which I understand to be essentially the same thing, just ground up finer) - and my LFS wouldn't believe me about it causing an ammonia spike until I left a bunch of it sitting in fresh dechloriated tap water for a week, then got them to spin test the water from that container against my regular tap water. They still have no idea what caused it beyond "some form of contaminate mixed into the sand", but at least we proved it was actually the cause. I know this doesn't help your problem but just to back you up and say I believe you when you say you think it's the coral causing the issue, as unlikely as that might seem on paper 🙂

[anamb95]

Hey there! Thanks for reaching out and thanks for the backup. 😊 That is absolutely bizarre about the sand! But I definitely believe it, as I've seen all kinds of substrates do weird stuff to aquarium water. I'm wondering the same thing about the coral, but what's weird is that my betta is perfectly fine, the water smells OK, and the test strips are showing different results than the liquid test kit. So either my liquid test kit is wrong, or my betta won the genetics jackpot lol. I was also reading that higher pH will cause a rise in ammonia because the ammonium from the low pH is converted into actual ammonia as the pH rises. But based on what my liquid test kit is showing, my betta should be dead. I dunno; I'm taking cues from him (watching carefully for any behavior changes) and will be doing once-weekly water changes for awhile to keep levels maintained.

Edited June 24 by anamb95

[anamb95]

Another update on the situation, per a user's advice. I tested three samples of water with my liquid API test kit before doing another water change. I did strictly ammonia. The leftmost sample is distilled water; the center sample is the tank water; and the rightmost sample is fresh, dechlorinated water treated with both API Stress Coat and Prime. So, even though the ammonia may not be at 8.0 ppm+ and the liquid test not affected by the Prime, something is still off. This is corroborated by a strip test I did at the same time, which is showing a small presence of nitrite. I did a 50% water change today. Miso is still doing fine, but I have noticed that since the pH is rising from the coral, there is a mass die-off of algae in the tank. I sucked up a lot from the sand and the decor (only to kick up more as I poured fresh water into the tank). This happened during last week's water change as well and will likely take several more water changes to completely remove from the tank. For now, I have decided to do once-weekly water changes--sucking up as much dead algae as I can--and take my cues from Miso. I will increase frequency of water changes if his behavior indicates signs of ammonia or nitrite poisoning and I will move him if need be. I will also be doing frequent tests, both liquid and strips, to monitor chemical levels. With enough time and patience, I think things will level out. Thanks for your feedback, everyone!