Growing plants without fertilizers or co2

[Burgermuncher]

Just got back from vacation, spent the day cleaning my tanks - the jungle vals are thriving, surprisingly. I've got a cheap Top Fin light on one of them, and a Nicrew G2 on the larger tank, still getting the hang of it. Went nearly 2.5 weeks without a water change, so that was a fun day of scrubbing and testing.

[shakinStevens]

Air has CO2, so increasing water-air mixing can actually add CO2 to the tank. My filter spray bar is positioned just below the water surface and points up and a bit sideways, creating a constant wave at the surface. Alternatively, you could create a small waterfall. With enough mixing, CO2 levels will stabilize at 10ppm CO2 with stable oxygen levels.

Many people using CO2 use diffusers and drop checkers, aiming for 30ppm CO2 levels. I tried this approach, but it required frequent monitoring to maintain stable CO2 flow. Too much CO2 can be deadly for fish. I switched to Passive CO2 and it's been much more efficient than diffusers, which release bubbles into the water. With Passive CO2, all CO2 dissolves in the water. I used to refill my paintball CO2 tank about three times a year with a diffuser. Since switching to Passive CO2, I've gone two years without a refill in my small shrimp tank.

The inverted bottle in the tank should be located in an area with water flow around the opening to ensure good mixing and a uniform amount of CO2 throughout the tank. I have my Passive CO2 system on a timer, so it's automatically refilled daily. I adjust the system so that it usually fills the container without overfilling. If it does overfill, the excess harmlessly bubbles out. You don't need a drop checker; my system has gone weeks without any adjustment.

With Passive CO2 and water-air mixing at the surface of my tank, I can be sure that CO2 and oxygen levels in the water are always stable. However, you also need nutrients in the water for plants to grow. There are 14 essential nutrients, and if one is missing, plants won't grow or will die. The biggest problem people have with plants is getting the fertilization right. Some fertilizers don't last long in the water, while others do. So, some people have to dose fertilizer every other day, while others only need it once a week.

Many fertilizer manufacturers assume you have nutrients in your tap water. But in today's world, everyone has different water. If you're using RO water, your water has no nutrients, leading to deficiencies. Having a lot of fish in the tank helps, as fish waste adds nutrients.

I personally use 100% RO water in my shrimp tank. With commercial fertilizers, I couldn't grow anything but algae. Only after I started making my own fertilizer did I have success with plants.

Due to the fertilizer issues, many people try using potting soil as the substrate. This can work if you choose the right product, but it's impossible to know which one will work best. Others use backyard soil or terrac in the substrate. It's a trial and error process. One problem with soil substrates is that the nutrients in the soil will eventually run out. Some people have to replace the substrate yearly or every other year. Many also refer to "old tank syndrome," where plants die and algae takes over. In my experience, this is mainly a nutrient issue.

Some people say some plants only work in tanks with CO2. No, that's not true. If the nutrient levels in your water are barely enough, some plants will grow while others will not. Some people only have luck with one type of plant in a tank, while all others fail to grow.

[julia]

Thanks heaps everyone for all the advice and suggestions.

I think I'll give Val a go, and also try my luck with some crypts and maybe hornwort. I might try using a bit of no-added fertilized soil under the substrate - since I won't have any burrowing fish, it should be fine. And I'll make sure there's good surface aeration to add some CO2 to the tank. I've got tank water rather than town water, which I think has fewer nutrients, so I might need the soil or a pretty heavily stocked tank to make it work.

I'm thinking of adding some frogbit from my current tank as a floating plant, and I was also considering adding some kind of houseplant like devil's ivy or a fern. Dwarf sagittaria and bloomi fern sound like great options if they can carpet - I've never had a carpeting plant before because I thought they'd be too high maintenance, but I might give these a try.

Has anyone on this forum had any experience with pearlweed or guppy grass? I'd love to hear about it.

And Burgermuncher, your tank looks absolutely stunning - what kind of angels are those?

[boomer]

Plants have unique needs when it comes to both light and nutrients, which are closely intertwined. Insufficient or excessive light can throw off the balance of nutrients, leading to poor results. Some plants you've listed require more of both.

In my experience, using soil as a substrate isn't the best approach. It can cause issues and may not provide any real benefits. In fact, within a year, it can become less effective than inert sand or fine gravel.

[TwinTankman]

I've got some experience with crypts and I've found they do well with some substrate ferts. I use Jobes Plant Spikes for my lush plants, they're great for ferns and palms. You can cut them to size, but they're not ideal if you like to replant often - the spikes can come loose and you'll be dealing with algae in no time.

I add new spikes every three months or so, and I've been using them for nearly 20 years now. They're super cheap and work a treat. I also use water column ferts, and I'm a big fan of Tropica's products. They've got two options - Premium Nutrition and Specialised Nutrition.

The Premium Nutrition one is great for tanks with slow-growing plants and lots of fish, it's got iron, magnesium, and micro nutrients but no nitrogen or phosphor. The Specialised Nutrition one is better for tanks with fast-growing plants, it's got nitrogen and phosphor as well as iron, magnesium, and micro nutrients.

If you don't want to fertilize your tank, you'll need to stick with slower-growing plants that don't need as much. Ferns and anubias are good options, and you can check out Tropica's list of easy-to-keep plants for more ideas.

[julia]

I've been meaning to get back to this thread for ages.

I'm considering trying out those spikes, but I'm also thinking of just dropping the crypts altogether - I tend to get a bit restless with my aquascapes and I'm not sure they'd appreciate all the changes.

Boomer, I was wondering, do you think it'd be better to have some soil in the tank, even if it's just going to break down over time, or to just go without any ferts at all? Are there any nutrients that the fish wouldn't be able to provide that the dirt could?

It seems like Val, hornwort and floaters are my safest bets, and maybe I'll give bloomi fern a go if I can find some. And I have to ask, am I the only one who thinks dwarf saggitaria looks just like mini vals?

[boomer]

I'm planning a low-maintenance tank with minimal setup, and I'm trying to avoid spending on Co2 and ferts. The tank will be slightly acidic and tropical.

I know plants need nutrition, but I'm looking for options that can thrive with minimal care. I already have java fern and java moss in a no-ferts/no-Co2 tank, so I'm thinking of adding those. Other possibilities I've considered are pearlweed, val, elodea, and hornwort. Maybe some crypts could work too.

Do any of these plants have a good chance of succeeding in a low-tech setup like this?

No, the only real benefit of using soil is the initial boost of CO2 from the organics, but that's short-lived. Even Diana Walstad, a well-known advocate for soil substrates, admits that after a year, there's no advantage to using soil over inert sand. It's just a mess waiting to happen, with a surge of ammonia at the start. Most experts recommend a dry start and a fishless period of six months to mitigate this issue, but it's still not worth the hassle. Substrate-digging fish, especially cories, are also out, as they're prone to bacterial problems with these types of substrates.

Using fertilizers is a much simpler solution. Whether it's substrate tabs for plants like large swords or liquid ferts, it's easy to ensure your plants get the micro-nutrients they need.

[GamePix]

I've also had great success with Jobe spikes for my plants, they work a treat for my Red Lotus which is just thriving and looking stunning. I've got a pretty low bioload in my 29 gallon tank with just four Corys, but the plants are all doing fantastically with the occasional fert dose every couple of months. My Java ferns, Anubias, and Christmas moss are all growing steadily, and the Ludwigia and Pogostomen are looking healthy and happy.