CO2 injector recommendations?

I am setting up a 300 gallon tank. While it won't be a garden tank, I would like to have a few nice Vallisnerias and other native plants. Is a CO₂ injection system the best way to go, and if so, can anyone recommend an appropriate system for a tank this size?

CO2 injection really isn't necessary. People use it when they want really fast growth under strong lights. To me, it's too much work to run and the faster growth make for too much garden maintenance.

Vals will grow just fine without it, as will just about any other true aquatic.

Thanks! That's the best reply I could get!

Another question:

If I have high light but no additional CO₂, will that stress the plants? The tank has a dozen 40W flourescents from its earlier life as a reef tank; should I take some of those out?

CO2 injection really isn't necessary. People use it when they want really fast growth under strong lights. To me, it's too much work to run and the faster growth make for too much garden maintenance.

Vals will grow just fine without it, as will just about any other true aquatic.

I agree - if your lighting isn't too intense, go with something along the lines of a Walstad tank. If you want to grow a lot of plants -- that is, a lot of variety and a lot of biomass -- then you can put together a pressurized system for less than $150.

But then you have to start thinking about lighting and fertilization and pruning and before you know it you have a whole other hobby going on. It's a fun one, though.

Personally, I think a big tank with a val monoculture would look fantastic.

Another question:

If I have high light but no additional CO₂, will that stress the plants? The tank has a dozen 40W flourescents from its earlier life as a reef tank; should I take some of those out?

I wouldn't consider 12 40w florescent tubes a whole lot of light, and I don't think it's enough to mandate CO₂ fertilization. If you are having trouble with algae you can always run most of them on a shorter photoperiod (i.e. less than 8 hours).

Edited by mette, 27 February 2008 - 01:01 PM.

Lighting should be just fine, assuming the tank is well planted. I agree with Mette - a monoculture val tank would be striking at that size.
If you find you need a shorter photoperiod, one way to do it is to have the lights come on in the morning, off during the day, and on again in the evenings. That way you get to see your plants! If you are trying to breed fish and some plants, though, this schedule might mess things up.

Lighting should be just fine, assuming the tank is well planted. I agree with Mette - a monoculture val tank would be striking at that size.
If you find you need a shorter photoperiod, one way to do it is to have the lights come on in the morning, off during the day, and on again in the evenings. That way you get to see your plants! If you are trying to breed fish and some plants, though, this schedule might mess things up.

Yes, grow us a tank full of giant vals! I think low-tech is the best means to that end actually, provided you have harder water and a somewhat rich substrate. At least, those would be my choices.

You can definitely break up the photoperiod - I'm thinking about trying that myself. I assume you have 6 twin-tube fixtures. With a couple timers you could run a step-up sort of thing: 160w morning and evening, all 480w for 4 hours or so midday. That saves you a few bucks on electricity, too (maybe $10/month). I think you could go whole hog with no problem, however.

Lighting should be just fine, assuming the tank is well planted. I agree with Mette - a monoculture val tank would be striking at that size.
If you find you need a shorter photoperiod, one way to do it is to have the lights come on in the morning, off during the day, and on again in the evenings. That way you get to see your plants! If you are trying to breed fish and some plants, though, this schedule might mess things up.

Thanks, y'all!

I'm not trying to breed any fish in this tank, but it is on display in a public building, so the light schedule will be geared towards the convenience of viewers (probably 8 am-6 pm or similar); additionally, the building lights are on round-the-clock. At least starting out the tank will probably not be well-filled with plants (I want to leave plenty of room for them to grow); will algae be more of a problem in that situation? Perhaps a lighting compromise can be reached.

Mette mentioned using a Walstad tank approach; that entails using a 2-3" layer of soil beneath the gravel, correct? Is there any reason I shouldn't confine the soil to the baskets or pots in which the plants are rooted? I'm just worried about suspended soil particles becoming a problem.

Sorry for all the questions. My planted tank experience up to now has consisted of dropping some hornwort and duckweed in my siren tank and leaving it to live if it can.

*EDIT* I didn't see Mette's second post til after I posted this. That sounds like a good plan. Unfortunately, the guys who set the tank up for saltwater just sort of jerry-rigged the lighting; I'll have to get an electrician to help sort it out.

Edited by Newt, 27 February 2008 - 01:32 PM.

I wouldn't worry about suspended soil. The gravel will keep it in place when you are finished, and anything that gets mixed up while gardening will be taken care of by the filter. DO NOT vaccuum the gravel!

I would put the soil all over because invariably you will move some of the plants around as time goes on. Plus, the vals will send of side shoots that will go outside the pots anyway.

If it were my tank, I would put down about 4 inches of soil (I'm assuming it's a tall tank here), so that the nutrients and carbon last longer. I would also mix in a lot of old leaves like maple/pecan/tulip poplar that break down easily, and maybe a few oak that will take longer to break down. (Just don't add walnut!).

Here's an important question - how tall is this tank? Can you reach the bottom for maintenance? If not, I would definitely go for the monoculture since you won't be worried about the way the plants are arranged together.

To block light (especially when the vals are filling in), you might want some large floaters like frogbit (Limnobium spongia) that spread fast yet are easy to remove.

I'm eager to see this tank when it is set up! What will be going in it? Be sure that it isn't something that wills root around in the substrate or you might have a mess...

The tank is 8 feet long, 3 feet high, and 3 feet wide. Once the plants and furniture are in place, they will not be moved unless necessary.

The total fish list is yet to be determined; the concentration will be on moderate-sized centrarchids (medium-to-large sunfish, rock bass, and possibly crappie and fliers) and larger minnows. I'll probably include some madtoms, too. None of those guys should be a problem as far as rooting, but I was also considering including some suckers and drum; they would probably keep soil in the water column if they could get to it. Would it help to use a deep layer of gravel on top of the soil (6" or more)?

Frogbit sounds like a good idea. Would waterlillies also work? The tank has a Tennessee native theme; fortunately Frogbit and a handful of waterlillies are native to the state.

Jeez, Nativeplanter wins again (if that's a Pyrennes in your avitar, then we're really on the same wavelength). Anywho, I'll post this for second place.

At least starting out the tank will probably not be well-filled with plants (I want to leave plenty of room for them to grow); will algae be more of a problem in that situation? Perhaps a lighting compromise can be reached.

I would want a pretty good stock of plants right off the bat. Plants -- especially vals in my experience -- don't really get going for a while, so generally more is better to get the tank settled in. My suggestion would be to stock plenty of vals as well as some hornwort and frogbit to get things going.

Mette mentioned using a Walstad tank approach; that entails using a 2-3" layer of soil beneath the gravel, correct? Is there any reason I shouldn't confine the soil to the baskets or pots in which the plants are rooted? I'm just worried about suspended soil particles becoming a problem.

My last Walstad tank used a 1.5" layer of soil covered by a 1.5" layer of coarse sand. The soil itself was equal parts yard dirt, kitty litter, and vermiculite. Next time I will skip the vermiculite, but otherwise it was great. For vals and other plants that spread by runners, I would prefer a soil underlayer to pots. My tank would get cloudy if I stirred the substrate, but it clears up pretty quickly. You don't really need to be stirring it anyhow - these tanks pretty much run on autopilot.

*EDIT* I didn't see Mette's second post til after I posted this. That sounds like a good plan. Unfortunately, the guys who set the tank up for saltwater just sort of jerry-rigged the lighting; I'll have to get an electrician to help sort it out.

I wouldn't worry about it. With the lights you described I don't see a serious problem with running them for a 12+ hour block. It's certainly not something I'd want to call an electrician over. Just don't start any fires is my motto.

One question is whether any of the centrachids would try to create a nest in the substrate. I don't know enough about the family, but I know many sunfish do. Problem is, having gravel too deep makes it hard to establish plants (the roots have to get to the dirt first). I suppose one option could be to plant the vals with an inch of gravel on top, then after they become established slowly add more gravel (over a few weeks/months). The roots would then be in the soil and any offshoots would get nutrients from the mother plant until it's roots get down far enough. But I'm not really keen on this idea for a public tank; I never tried something like it.

Water lillies would work, but you would want to be able to see the top of the tank to appreciate them. They will also shade out the vals in time. But it would look cool, with lilly petioles coming up, and would virtually nix any algae problem underneath once they are well established (it would be very, very shady).

Or, you could culture a lot of frogbit in a different tank before you set it up to cover a lot of the surface. If you can then somehow keep it confined to non-planted sections for a while, even better.

I agree to skip the vermiculite. If it does get stirred up a little, it's density seems to make it settle and not get picked up in the filter. It looks rather unnatural this way, and the scooting fish turn it into little swirling clouds.

Mette - it is a Pyrenees. He protects the house from Vikings and other sundry dangers.

The tank is 8 feet long, 3 feet high, and 3 feet wide. Once the plants and furniture are in place, they will not be moved unless necessary.

The total fish list is yet to be determined; the concentration will be on moderate-sized centrarchids (medium-to-large sunfish, rock bass, and possibly crappie and fliers) and larger minnows. I'll probably include some madtoms, too. None of those guys should be a problem as far as rooting, but I was also considering including some suckers and drum; they would probably keep soil in the water column if they could get to it. Would it help to use a deep layer of gravel on top of the soil (6" or more)?

Frogbit sounds like a good idea. Would waterlillies also work? The tank has a Tennessee native theme; fortunately Frogbit and a handful of waterlillies are native to the state.

I think lilies would be very cool - how about Nuphar? They might be a good candidate for potting, so you can remove them if they start shading out the rest of the tank or otherwise cause a problem.

10+ inches of substrate sounds too deep to me, but others may have experience to the contrary. I think 2" of soil and 3-4" of gravel or sand would be about as deep as I would go, but I have never set up anything bigger than 75 gallons. I would suggest beefing up the soil layer with some dolomite, red clay, and leaf mold or peat.

I wouldn't worry about cloudiness too much, especially if you have several inches of top layer. I had to do some pretty serious uprooting to cause a problem in my tank, most of the time water clarity was excellent. Consider mechanical water polishing (polyfloss, sponges) if you expect your livestock to dig much.

Mette - it is a Pyrenees. He protects the house from Vikings and other sundry dangers.

Fantastic - mine is just the same. No one will ever get to Marshmallow's invisible flock of sheep.

Thanks, y'all!

What do you think about a thinner layer of mixed rock sizes as a rooting deterrent: if I include a layer of cobble-sized stones with smaller rocks between, the suckers should be unable to reach the soil, right? It's worth a shot, anyhow.

Many of the centrarchids and cyprinids I intend to keep are gravel nesters, but they don't move stones any larger than they can fit in their mouths; the suckers will be much more troublesome stone-shifters.

Keeping the waterlillies in pots is a good idea. I have a pond at home I can put them in once the submersed plants get going. I may put any excess frogbit in that pond, too; the algae in it has gotten out of hand since the neighbors cut a bunch of trees that once shaded the pond.

If it were my tank, I would put down about 4 inches of soil (I'm assuming it's a tall tank here), so that the nutrients and carbon last longer. I would also mix in a lot of old leaves like maple/pecan/tulip poplar that break down easily, and maybe a few oak that will take longer to break down. (Just don't add walnut!).

Not to derail, but a quick question...Why no walnut leaves? I may have answered my own question when I discovered the toxicity of a substance walnut produces. But again I ask the expert. And also, is it bad for fish or plants if used as a tanning agent in a canister, or just it just need to be kept out of reach of roots of other plants?

Walnut is a very allelopathic plant, meaning that it secretes a toxin that inhibits the growth of (and even kills) other plants (in this case, a chemical called Juglone). Some species of walnut have more than others, but the result would be disasterous in the tank. DO NOT use ANY part of walnut (leaves, bark, wood, etc) in your tank or ANY tank processes (like as a tanning agent). In fact DO NOT use soil from near a walnut tree, as the soil will also contain these compounds. (note - I do not know if it has any effect on fish)

Not to derail, but a quick question...Why no walnut leaves? I may have answered my own question when I discovered the toxicity of a substance walnut produces. But again I ask the expert. And also, is it bad for fish or plants if used as a tanning agent in a canister, or just it just need to be kept out of reach of roots of other plants?

Just as an example, here's a picture of my boyfriend's subtropical that's planted primarily with val. Couple of other plant odds and ends but definitely mostly val. I really love it.



No CO2, no heater, canister filter and HOB for current, Eco-complete substrate and I think either 80 or 120 watts of generic fluorescent (can't remember if one of the light fixtures has two bulbs or just one). 75 gallons.

That tank looks great, Threegoldfish; I hope mine fills in like that. Mine won't be all vals, though; I hope to get some of the nice reddish Potamogeton and maybe some Myriophyllum, Cabomba, Elodea, and other native submersed species going.

Walnut is a very allelopathic plant, meaning that it secretes a toxin that inhibits the growth of (and even kills) other plants (in this case, a chemical called Juglone). Some species of walnut have more than others, but the result would be disasterous in the tank. DO NOT use ANY part of walnut (leaves, bark, wood, etc) in your tank or ANY tank processes (like as a tanning agent). In fact DO NOT use soil from near a walnut tree, as the soil will also contain these compounds. (note - I do not know if it has any effect on fish)

I have also heard that you should avoid related nut trees: black walnut, English walnut, pecans, etc. Hickory and oaks are OK.