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My tank's been showing ammonia spikes lately, around 0.5 ppm, even after weekly water changes. It's a 20-gallon planted tank with a sponge filter, and I've got a few Neon Tetras and a Betta. Any ideas what's causing this?

Ammonia spikes can happen if the biofilter isn't fully established or if there's overfeeding. How long has the tank been running? Also, what's your feeding routine like? Overfeeding is a common culprit, especially with Bettas.

Thanks for the quick response. The tank's been up for about 3 months, and I feed once a day, just a pinch of flakes. Maybe I'm overdoing it?

Yeah, that sounds like too much food. Bettas are prone to overeating, and uneaten flakes can decay fast. Try cutting back to every other day or switching to pellets. They're easier to portion.

Another thing to check is your water conditioner. Some don't detoxify ammonia, just chlorine. If you're using a basic one, switch to something like Seachem Prime. It'll help buffer the ammonia while the biofilter catches up.

creek wrote: ↑Sat Jun 28, 2025 8:36 am Another thing to check is your water conditioner. Some don't detoxify ammonia, just chlorine. If you're using a basic one, switch to something like Seachem Prime. It'll help buffer the ammonia while the biofilter catches up.

Prime's a lifesaver, no cap. I'd also test your tap water. Sometimes it's got ammonia straight from the source.

Agreed on testing the tap. Also, how often are you cleaning the sponge filter? If it's too clean, you might be removing beneficial bacteria. Rinse it in tank water during changes, not tap.

If the tank's only 3 months old, the biofilter might still be stabilizing. Adding a bacterial starter like Tetra SafeStart could speed things up. I've had good results with it in new setups.

Yo, same thing happened to my 20-gallon. Turned out my substrate was leaching ammonia. If you've got dirt or certain planted tank substrates, they can mess with params. What's under your gravel?

bruh, check your dead plants too. if any are rotting, they'll spike ammonia like crazy. had that happen last month, took forever to figure out.