Who Gives A Fish Forums

Been wondering about this lately, got me thinking of getting a new test kit.

My tank's got a RTBS (adult), a Bristlenose plec (adult), 10 harlequin rasbora (getting on a bit, nearly 5 years old), and a bunch of assassin snails (started with just 2).

Plant-wise, I've got a few Anubis varieties - congensis is doing alright on the bogwood, but it's slow going, hetrophylia, and nana bonsai. Microcosm Windelov's going crazy, blocks the filters and powerheads if I don't keep on top of it. Vallis are breeding and spreading along the bottom, and my Java fern's been in there for years, now it's 4 plants strong with more on the way.

Tank's a 5ft x 18in x 18in, filtered with a tec 1200, a powerhead, and 2 t8 plant biased 4ft flouresants on a timer, giving me about 5 hours of light a day. I'm using liquid Ei ferts, 50ml mcora and 50ml micro twice a week, and I've got a big chunk of bogwood in there. Seemed like a good balance, but now I'm having doubts.

My filter's been in there for years, was fully cycled when I got it, made setting up a breeze. But now, 6 or 7 years on, I've had fish come and go, some from old age, others from illness... and I'm starting to wonder if I've got enough fish to keep the filter going, or if the plants are doing all the work.

It's a good problem to have, I know, but I'm thinking of adding more fish, maybe some shrimp. Always fancied it, and with the plants providing plenty of hiding spots, it could work. But what if I increase the stock and the filter's not processing enough ammonia? Am I just being paranoid?

I think I can help alleviate your concerns, squidink. It's worth noting that plants tend to take up ammonia more quickly than nitrifying bacteria. This is especially true for faster-growing plants, as they require more nitrogen and prefer ammonia or ammonium as their source.

In a well-planted tank like yours, with fast-growing plants like Microcosm Windelov, the majority of ammonia is likely being used by the plants. I've heard floating plants referred to as "ammonia sinks" due to their ability to absorb large amounts of ammonia.

Regarding your concerns about the nitrifying bacteria, don't worry – they don't suddenly disappear or die off when ammonia levels drop. Once established, Nitrosomonas sp. bacteria can enter a state of dormancy, allowing them to survive periods of low ammonia. However, factors like temperature, pH, and overall plant health can impact their ability to survive.

In terms of adding more fish, I'd say you're unlikely to overstock your tank from an ammonia perspective, given the growth of your fast-growing plants. Of course, there are many other factors to consider, but when it comes to ammonia, your plants should be able to handle the additional load.

Thanks for the reassurance, I was probably overthinking it, but better safe than sorry, right?