My cycling tank keeps becoming acidic?

Hello, all~
I've been cycling my tank for about a week now-- though the process hasn't been entirely consistent. I was dosing with fish flakes and it made my fish tank an absolute mess, so I vacuumed it up and didn't add anything else until my pure, liquid ammonia arrived today. In general, however, I've been testing my fish tank's pH on a daily basis with the results usually coming back between the 7.0-7.6 range. The past 2-3 days, however, my tank acidity has been dropping down to 6.0; the color comes back bright yellow in the test tube sample.

I keep performing major water changes, usually between 30-40%. I'll re-test the pH and find it sitting at a healthy blue color, around 7.2 or so, but the next day when I test it again it will have dropped down to 6.0... Again, this wasn't a problem before, it's only happened 2-3 times, but when I'm anxious to get my tank cycled (and not have the pH drop down on a daily basis so that it becomes dangerously acidic to my livestock) it's worrying. Today, I performed a major water change (40%, and mostly because I added way too much pure ammonia to my tank) and I added more water than what I had before to increase the water line, but the pH sat only at a 6.8 when I tested it.

I read that driftwood can increase the acidity of your tank but I can't imagine it lowering my pH that much, and on a near-daily basis, and with major water changes. Extra info: my tank is 10 gallons and is about a week into cycling. I use Aqueon Shrimp and Plant Substrate, and was dosing with a bit of Seachem though stopped a couple of days ago. Today I added a Fluval nano CO2 diffuser, and I keep my aquarium at 80F. TIA!

 

It would appear that you have soft water (i.e. water with a low KH and GH). The KH (carbonate hardness) will tell you how resistant your water is to a change in pH. With a higher KH your pH will be much more resistant to change, whereas with a low KH your water is not as resistant to pH changes.

Additionally, when your pH drops below 7.0, the ammonia in your tank starts turning into ammonium, and by the time your pH gets down to 6.0, all ammonia has turned into ammonium. The good thing about ammonium is that it is far less toxic to fish (some claim it is non-toxic). The bad thing is that ammonium is a bad food source for the bacteria and the colony will not develop. So when your pH get down near 6.0, it may become impossible to cycle the tank.

I too have a low KH. To counteract this, I put crushed coral in my filter. But with a 10 gallon tank, you could just put a cuttle bone (you know, those things they sell in the bird department) right into your tank. This too will raise the calcium/carbonate level in your tank making your pH much more stable.

Best of luck!

 

I agree with above post. Water changes will mess with your cycle.
First do you have fish in the tank-likely no since you’re adding ammonia.
I’d stop doing water changes and add some buffering compound. Simple baking soda can do it. Crushed coral can work but if you’re ph is dropping to 6 crushed coral or cuttle bone might not be enough. There are also commercially available compounds you can buy to do this.
I’d start with baking soda then go front there. Keep your ph about 7.

 

wow, I've had an almost identical situation happen to me while trying to cycle my tank. The ammonia overdose and the PH drop—all that. It was a dumb noob error on my part (I'm new to fish keeping) and I recently identified the cause of my PH drop. I'll share, perhaps it will help. In the end, the cause of my PH drop was using Tetra Easy Balance Weekly. This was one of the first products I purchased, it says "Maintains healthy water - Regulates ideal PH - Reduces frequent water changes", when I read "Regulates ideal PH" my brain interpreted that as "oh anything this product touches magically turns to the ideal PH, prolly 7.0" - the reality is that this product drops the PH like crazy and I had been adding it to the tank AND to the water I was adding in to refill/water change. A mess.

Take some test tube samples of water using your master test kit, add the PH drops and once you have color change go ahead and add a drop of the products you're using to each and see if any of them affect the PH. My water PH from the sink was 7.0 then I added one drop of the Tetra Easy Balance and the water instantly turned almost clear/yellow. That was the source of my issue the whole time! Did a few water changes afterward to help cleanse my tank of it cause I'm sure it was on everything and in the substrate. Now I'm back in business! Here I am adding this product thinking I'm hooking my tank up when in reality I was overdosing and sabotaging myself.

Also, one last thing worth noting. You can purchase crushed coral from any pet store and that will cause the PH of your tank to increase! A little goes a long way. I recommend adding some crushed coral to a test tube sample and watch it change, it's incredibly effective. I added a small amount (size of a dime) to a mesh bag and put it in my hang-on filter to help bump up the PH a bit after my ordeal. I wouldn't add it loose to the substrate, add it in a way that allows you to undo it if you want.

Good luck!





also, a link to my thread if you're curious how it all played out! Very similar to what you have going on. Drift wood and ammonia overdose all documented. Need Advice: next steps for my first ever cycling | Aquarium Nitrogen Cycle 433959

 

wow, I've had an almost identical situation happen to me while trying to cycle my tank. The ammonia overdose and the PH drop—all that. It was a dumb noob error on my part (I'm new to fish keeping) and I recently identified the cause of my PH drop. I'll share, perhaps it will help. In the end, the cause of my PH drop was using Tetra Easy Balance Weekly. This was one of the first products I purchased, it says "Maintains healthy water - Regulates ideal PH - Reduces frequent water changes", when I read "Regulates ideal PH" my brain interpreted that as "oh anything this product touches magically turns to the ideal PH, prolly 7.0" - the reality is that this product drops the PH like crazy and I had been adding it to the tank AND to the water I was adding in to refill/water change. A mess.

Take some test tube samples of water using your master test kit, add the PH drops and once you have color change go ahead and add a drop of the products you're using to each and see if any of them affect the PH. My water PH from the sink was 7.0 then I added one drop of the Tetra Easy Balance and the water instantly turned almost clear/yellow. That was the source of my issue the whole time! Did a few water changes afterward to help cleanse my tank of it cause I'm sure it was on everything and in the substrate. Now I'm back in business! Here I am adding this product thinking I'm hooking my tank up when in reality I was overdosing and sabotaging myself.

Also, one last thing worth noting. You can purchase crushed coral from any pet store and that will cause the PH of your tank to increase! A little goes a long way. I recommend adding some crushed coral to a test tube sample and watch it change, it's incredibly effective. I added a small amount (size of a dime) to a mesh bag and put it in my hang-on filter to help bump up the PH a bit after my ordeal. I wouldn't add it loose to the substrate, add it in a way that allows you to undo it if you want.

Good luck!


View attachment 650193

also, a link to my thread if you're curious how it all played out! Very similar to what you have going on. Drift wood and ammonia overdose all documented. Need Advice: next steps for my first ever cycling | Aquarium Nitrogen Cycle 433959

Wow! Such an in-depth response! I'm glad to hear you can relate, though, and that I'm not the only one who screwed up like this. I'll definitely have to try testing what could be making the water acidic, though I'm not really adding anything, strictly-speaking. I had stable levels before, too. I've never heard of such a thing... At least this hobby keeps you on your toes.

Oh, by the way, is your cycling complete? Have you added any fish?

It would appear that you have soft water (i.e. water with a low KH and GH). The KH (carbonate hardness) will tell you how resistant your water is to a change in pH. With a higher KH your pH will be much more resistant to change, whereas with a low KH your water is not as resistant to pH changes.

Additionally, when your pH drops below 7.0, the ammonia in your tank starts turning into ammonium, and by the time your pH gets down to 6.0, all ammonia has turned into ammonium. The good thing about ammonium is that it is far less toxic to fish (some claim it is non-toxic). The bad thing is that ammonium is a bad food source for the bacteria and the colony will not develop. So when your pH get down near 6.0, it may become impossible to cycle the tank.

I too have a low KH. To counteract this, I put crushed coral in my filter. But with a 10 gallon tank, you could just put a cuttle bone (you know, those things they sell in the bird department) right into your tank. This too will raise the calcium/carbonate level in your tank making your pH much more stable.

Best of luck!

Thank you for your response! I also have a question about pH and fish... How important is it for fish/crustaceans to have a pH in their "recommended" zone? I thought the recommended pH range was something you strictly had to adhere to, but it seems like a lot of things I've read imply that there is room for variation. Like Ember Tetras prefer slightly acidic water, but a mystery snail prefers slightly basic water... So would either of them be affected greatly if I kept the pH range around 6.8-7.6?

 

All but the most delicate fish will do just fine in any pH between 6.0 and 8.4. PH can become important when trying to get fish to breed. Many fish want a specific pH before they will spawn.

Snails prefer a higher pH, because a higher pH means there is more calcium in the water, which they need to keep their shells from denigrating.

 

I agree with above post. Water changes will mess with your cycle.
First do you have fish in the tank-likely no since you’re adding ammonia.
I’d stop doing water changes and add some buffering compound. Simple baking soda can do it. Crushed coral can work but if you’re ph is dropping to 6 crushed coral or cuttle bone might not be enough. There are also commercially available compounds you can buy to do this.
I’d start with baking soda then go front there. Keep your ph about 7.

Meant to respond to you earlier though I kept forgetting, but wanted to get back to you... I tried the baking soda method and it worked 100%; I couldn't believe it was as simple as that and am thankful that I didn't have go out and buy anything else. Even several days later the aquarium pH has remained stable. Thanks for the input!

 

It would appear that you have soft water (i.e. water with a low KH and GH). The KH (carbonate hardness) will tell you how resistant your water is to a change in pH. With a higher KH your pH will be much more resistant to change, whereas with a low KH your water is not as resistant to pH changes.

Additionally, when your pH drops below 7.0, the ammonia in your tank starts turning into ammonium, and by the time your pH gets down to 6.0, all ammonia has turned into ammonium. The good thing about ammonium is that it is far less toxic to fish (some claim it is non-toxic). The bad thing is that ammonium is a bad food source for the bacteria and the colony will not develop. So when your pH get down near 6.0, it may become impossible to cycle the tank.

I too have a low KH. To counteract this, I put crushed coral in my filter. But with a 10 gallon tank, you could just put a cuttle bone (you know, those things they sell in the bird department) right into your tank. This too will raise the calcium/carbonate level in your tank making your pH much more stable.

Best of luck!

I agree with this and cuttle bone or wonder shells will do the trick.

 

Meant to respond to you earlier though I kept forgetting, but wanted to get back to you... I tried the baking soda method and it worked 100%; I couldn't believe it was as simple as that and am thankful that I didn't have go out and buy anything else. Even several days later the aquarium pH has remained stable. Thanks for the input!

Happy to help and glad it worked out so well.
Just keep an eye on the PH and KH but should hold steady.

 

I also have very soft water and crushed coral does work, cuttlebone does nothing. You can add the crushed coral to your filter or as a substrate.