Old, but still good questions.
I've done a few tanks with dirt covered with gravel, and about 1" of dirt seems to be enough to provide a good rooting medium for plants. I can't say that dirt in excess of 1" is bad for a tank, but it will add to the time it takes to (finally) get the tank water to clear up, no matter how carefully you add the gravel (or sand) on top of the dirt. Whether adding the dirt dry or wet probably doesn't matter too much since I'd recommend dampening the dirt before putting the gravel or sand on top of it anyway; it helps to hold down the dust. No matter where you mix the dirt and water, it's going to be messy, dusty, and probably smelly. Which is easier to clean up?
As to preventing the dirt and top layer mixing, probably the less water in the tank, the better.
My tank water always seems to end up full of dirt, suspended particles, and sometimes even tannins from the stuff the dirt is made of, and I always anticipate a few weeks of water-cleaning followed by "polishing" and tannin removal, if necessary. I've learned to be patient and no longer try to add plants of fish until the water is clean and clear enough to polish.
Everyone has a favorite dirt, from $5 for 30 pounds at Home Depot to the expensive stuff developed for fhis tanks (and a lot more expensive than $5!). I think a lot of it depends on what you can reasonably expect the tank to look like when you're finished. If you just want a "fish tank" for your home-office, then cheap is reasonable. If you're competing for the best tank on the East Coast, you're probably not going to buy your dirt at the dollar store. Your choice, but if it's your first tank, then think "let's try this cheap until I figure out what I can reasonably expect to accomplish."
I favor organic soils from Home Depot with an emphasis on avoiding tannins, bark, perlite (Yikes, what a mess!), and time-release fertilizers. Time-released fertilizers aren't really organic, and how long they take to dissolve completely is another matter, and, aquatic plants will get most of their fertilizer in the direct form of ammonia from fish urine which will be directly absorbed by the plant's leaves from the water. Everything else is in the soil. One could, I suppose, dig up some soil from their garden and not do any harm. Crude, true enough, but effective (and cheap!), and any bugs that come in with the soil either become fish food, plant food, or part of the nutrient mix. Avoid centipedes and millipedes since they secrete hydrogen cyanide, which might not be too good for fish, but other than that....
Yup, clarifying the water after a setup takes time, mostly dependent on how careful you were when putting the tank together. My first tank probably took six weeks to clean up, the dirt, floating gunk, tannins, etc. I probably did everything wrong, starting with my dirt choice and right out to my filter media choices. Not to forget the tannins which, even when the water was clean, were so dark that you couldn't see from one end of the tank to the other. Well, we live, we learn.
Here's a thought: I usually like cannister filters for anything larger than 10 gallons. You can buy bulk materials and cut your own filter medium to fit whatever basket (or whatever) type of container the filter uses, and the cost is way cheaper than buying the manufactured filters the manufacturer sells. With a new tank, coarse filters can be washed out in the sink and reused until they are literally in shreds, and yet still be effective when wadded up. You're going to clean a lot of filters, maybe even daily if my first tank was typical.
The other thing I like about cannister filters is all those hoses, and the fact that adding a UV light in the future is much simpler if you just route the output of the cannister filter to the input of the UV fixture. Every part you could ever possibly need to connect the filter to the UV, and from the UV to the tank, fixtures, adapter, valves, hoses, etc., are all available at ACE Hardware. Plan well and you'll not buy a lot of parts you don't need, or don't fit, and in an afternoon you can assemble a pretty-classy tubing Rube Goldberg that doesn't leak and actually works.
When you're ready to polish the water you've already learned how to taper your filter medium from coarse to fine, what materials clean up easily, and can be reused, and that you only need a small amount of polishing media at the finer end of the chain if the coarser media is effective.
Tannins will require specialized filtering chemicals that can be recharged after absorbing their maximum in tannins - as well as a reminder that avoiding tannins in the first place is easier than removing them later. And do buy their little, but horribly expensive filter bags as cheaping-out and using a standard filter-media bag usually results in a tank full of little-tiny white balls (brown, and less noticeable after they've absorbed their fill of tannins you'll never get rid of), as well as another jar or jug of (expensive) tannin remover and the aforementioned specialized filter bag(s) you'll end up buying the second time.
If you're like most first-timers you'll have already added a few plants (they will have died), and maybe even a few fish who will by now have developed the fishy equivalent of black-lung disease, assuming they're still alive, and you'll have realized that you probably should have waited a bit longer before introducing plants or fish. We've all done it.
But, it you water is polished-clean, plants and fish are now due. Unless you have in mind a clear picture of what you want the planted tank to look like, or have already ordered a "packaged-set" of plants picked out for you and your water, or are constructing a show-tank just like one in a book or magazine, you have two or three choices. 1. Get plant stems, cuttings, and other plant parts from friends or club-mates; 2. Order some interesting specimens from an online retailer, or 3. Buy some from a local pet store.
Initially, stem plants are easy, grow fast, and are not usually invasive. But, their leaves tend to be small and, for their size, don't produce a lot of oxygen. The good news is they're expendable and if/when you get tired of them you can pull them out and (probably) they won't come back. Plants with larger leaves are slower starters, usually. Try to see whatever plants you get growing in a tank so that you can see whether they're taking over the tank or are happily getting along with other plants. You really do not want an invasive species in your tank.
Not all plants get along well together. Some plants produce alleles that will all-but-kill other types of plants in a small, enclosed tank. Not that that's a bad thing (especially if they're death on invasive species, but then invasive species are invasive because they resist most forms of control). Alleles are the chemical warfare of the plant world. It's part of the process, so if some plants don't work, try others until you get a happy mix.
Fish: your choice. If you plan to keep Cichlids, then don't be surprised when they rearrange, by which I mean totally destroy, plants in your tank, push the gravel around, expose the soil, dirtying the water, then die from the turbidity and turgidity. Or, go with a community tank of inexpensive, but colorful fish. Or, whatever you want. Fish produce CO2, which plants need for respiration, and plants produce O2 which fish need for respiration. Don't worry about micromanaging the perfect symbiotic mix of plants and fish for the perfectly functioning tank. Only nature does ecosystems well, and your tank will balance itself quite well if you don't try to metaphorically push worms up straws.
And, if it doesn't work out, well, you can always try again, but I can pretty much guarantee that a functional and healthy planted tank will require less maintenance, less filter cleaning, less water changes, and less stress that a sterile fish-only tank that's always on the verge of self-destruction.
A word about pathogens. Any sick fish is either a sign of an unhealthy tank or was, more likely, sick when introduced into the tank. You're going to occasionally introduce ick, or some other disease. It happens.
I mentioned earlier that one of the things I like about cannister filters is their easy adaptation to adding a UV "filter." First, UV does not kill anything. It scrambles DNA and RNA and usually prevents organisms from reproducing, or if they do manage to reproduce, their progeny are usually sterile. UV does not kill pathogens. It will, however, alter free-floating algae and generally prevents "green-water" in tanks that have living plants.
But, to be effective, any living organism must pass through the UV radiation to be affected. This means that filamentous algae that lives on rocks, gravel, wood, or any other damned place it feels like it can't be controlled by UV. If your UV system is on the outflow of a cannister filter, any organism you want, or hope it will kill must pass through the filter system before it gets to the UV light. Many organisms are so tiny that they actually will pass through the UV light, so this is a good thing. But not organisms that live on rocks, gravel, plants, wood, fish, snails, shrimp, frogs, or whatever.
Likewise, any UV light that is immersed into a tank, or hangs from the side, inside of a tank, cannot possibly be very effective, can it? I mean, if it's light is potent enough to destroy the DNA of passing pathogens, then it should also scramble the DNA of any fist, snail, or invertebrate that gets that close too, right? I don't recall reading any warnings on any of those types of UV light warning that fish should be kept at least three inches away, so I have to assume that they only value they might possibly have would be in scrambling the DNA of anything dumb enough to actually live on the light, like, maybe algae. Save your money.
Increasingly, UV disinfectors are using LEDs instead of bulbs with fluorescing coatings, or which there are two main varieties: cheap and expensive. The cheap ones, it's claimed, don't really kill pathogens though they may kill water-borne algae. The expensive ones claim to kill all pathogens because they're more powerful, or more concentrated, or create more UV radiation. We're talking about $80 versus $300+. Is there, or do they have a point? Yes, and no.
In reality, the rules above still apply: To have its DNA scrambled, any organism must pass within millimeters of the UV source, so anything that clings to rocks, wood, or fish isn't likely to go through the UV radiation, and so, will be unaffected. Can you really sterilize an entire fish tank, let alone all of the organic and inert objects within it? No. Once a fish has a pathogen living in or on it, UV won't help. What about spores of pathogens? Well, if they pass the UV, maybe, but if they settle to the tank bottom, no.
The best way to protect fish from disease is to, first, not introduce diseased fish into the tank in the first place, and second, maintain a healthy tank - which means one with plants and a symbiotic, functioning ecosystem in place - and let the fish's own immune system protect it from disease.
Speaking of an ecosystem we read a lot about the hand-wringing accompanying the question of whether one can "engineer" a healthy ecosystem, and if so, how to go about doing so. I like to think that life is either self-balancing or self-destructing, depending on what it see as correct. If an ecosystem is out of balance it will either eventually become more unbalanced, in which case, speaking of a fish tank, for example, the fish and plants will begin to die off and there's not much you can do. Or, the system will balance itself out, the fish and plants will thrive, with the odd and occasional minor disaster or dead fish passing away due to old age, aggression by other fish, or whatever, and it will simply "work" without much human intervention. When a large fish dies, I usually notice it. But when small ones go, I don't necessarily see it, and the system cleans up its own messes without my help or intervention.
I like to use a pre-filter on my tanks, a porous cellulose filter that traps the big gunk and keeps it from clogging the main filter. If the gunk is edible, something will eat it; if not, it will disintegrate into constituent components and eventually pass into the filter where I presume it will be organically treated, or trapped. Water changes are about two to four times a year, as are filter cleanings. Once every year or two something seems to plug the filter up a bit and I'll notice that the stuff on the surface isn't going around in circles at its usual pace, and I'll clean the filter, often as not, failing to find the reason for its slowing down. Cleaned up, it's happily spinning water around again.
No bubbles that would upset the balance of O2 to CO2, no surface water turbulence that would do the same thing. An never, ever any charcoal that would remove all of that free plant food in the form of ammonia my fish happily produce as a part of their daily lives. Vacuum the bottom? There's nothing there to vacuum. Oh, and a happy plethora of trumpet snails that only come out at night to forage and clean up whatever it is that they eat. They maintain their own balance of snails-versus-snail food; I don't know how; I doubt they give it much thought either. They disappear with the light, crawling off into the dirt, or at least I assume they do, and I suspect they prevent anaerobic conditions from occurring in the soil. I don't know; they're not saying.
I've done a few tanks with dirt covered with gravel, and about 1" of dirt seems to be enough to provide a good rooting medium for plants. I can't say that dirt in excess of 1" is bad for a tank, but it will add to the time it takes to (finally) get the tank water to clear up, no matter how carefully you add the gravel (or sand) on top of the dirt. Whether adding the dirt dry or wet probably doesn't matter too much since I'd recommend dampening the dirt before putting the gravel or sand on top of it anyway; it helps to hold down the dust. No matter where you mix the dirt and water, it's going to be messy, dusty, and probably smelly. Which is easier to clean up?
As to preventing the dirt and top layer mixing, probably the less water in the tank, the better.
My tank water always seems to end up full of dirt, suspended particles, and sometimes even tannins from the stuff the dirt is made of, and I always anticipate a few weeks of water-cleaning followed by "polishing" and tannin removal, if necessary. I've learned to be patient and no longer try to add plants of fish until the water is clean and clear enough to polish.
Everyone has a favorite dirt, from $5 for 30 pounds at Home Depot to the expensive stuff developed for fhis tanks (and a lot more expensive than $5!). I think a lot of it depends on what you can reasonably expect the tank to look like when you're finished. If you just want a "fish tank" for your home-office, then cheap is reasonable. If you're competing for the best tank on the East Coast, you're probably not going to buy your dirt at the dollar store. Your choice, but if it's your first tank, then think "let's try this cheap until I figure out what I can reasonably expect to accomplish."
I favor organic soils from Home Depot with an emphasis on avoiding tannins, bark, perlite (Yikes, what a mess!), and time-release fertilizers. Time-released fertilizers aren't really organic, and how long they take to dissolve completely is another matter, and, aquatic plants will get most of their fertilizer in the direct form of ammonia from fish urine which will be directly absorbed by the plant's leaves from the water. Everything else is in the soil. One could, I suppose, dig up some soil from their garden and not do any harm. Crude, true enough, but effective (and cheap!), and any bugs that come in with the soil either become fish food, plant food, or part of the nutrient mix. Avoid centipedes and millipedes since they secrete hydrogen cyanide, which might not be too good for fish, but other than that....
Yup, clarifying the water after a setup takes time, mostly dependent on how careful you were when putting the tank together. My first tank probably took six weeks to clean up, the dirt, floating gunk, tannins, etc. I probably did everything wrong, starting with my dirt choice and right out to my filter media choices. Not to forget the tannins which, even when the water was clean, were so dark that you couldn't see from one end of the tank to the other. Well, we live, we learn.
Here's a thought: I usually like cannister filters for anything larger than 10 gallons. You can buy bulk materials and cut your own filter medium to fit whatever basket (or whatever) type of container the filter uses, and the cost is way cheaper than buying the manufactured filters the manufacturer sells. With a new tank, coarse filters can be washed out in the sink and reused until they are literally in shreds, and yet still be effective when wadded up. You're going to clean a lot of filters, maybe even daily if my first tank was typical.
The other thing I like about cannister filters is all those hoses, and the fact that adding a UV light in the future is much simpler if you just route the output of the cannister filter to the input of the UV fixture. Every part you could ever possibly need to connect the filter to the UV, and from the UV to the tank, fixtures, adapter, valves, hoses, etc., are all available at ACE Hardware. Plan well and you'll not buy a lot of parts you don't need, or don't fit, and in an afternoon you can assemble a pretty-classy tubing Rube Goldberg that doesn't leak and actually works.
When you're ready to polish the water you've already learned how to taper your filter medium from coarse to fine, what materials clean up easily, and can be reused, and that you only need a small amount of polishing media at the finer end of the chain if the coarser media is effective.
Tannins will require specialized filtering chemicals that can be recharged after absorbing their maximum in tannins - as well as a reminder that avoiding tannins in the first place is easier than removing them later. And do buy their little, but horribly expensive filter bags as cheaping-out and using a standard filter-media bag usually results in a tank full of little-tiny white balls (brown, and less noticeable after they've absorbed their fill of tannins you'll never get rid of), as well as another jar or jug of (expensive) tannin remover and the aforementioned specialized filter bag(s) you'll end up buying the second time.
If you're like most first-timers you'll have already added a few plants (they will have died), and maybe even a few fish who will by now have developed the fishy equivalent of black-lung disease, assuming they're still alive, and you'll have realized that you probably should have waited a bit longer before introducing plants or fish. We've all done it.
But, it you water is polished-clean, plants and fish are now due. Unless you have in mind a clear picture of what you want the planted tank to look like, or have already ordered a "packaged-set" of plants picked out for you and your water, or are constructing a show-tank just like one in a book or magazine, you have two or three choices. 1. Get plant stems, cuttings, and other plant parts from friends or club-mates; 2. Order some interesting specimens from an online retailer, or 3. Buy some from a local pet store.
Initially, stem plants are easy, grow fast, and are not usually invasive. But, their leaves tend to be small and, for their size, don't produce a lot of oxygen. The good news is they're expendable and if/when you get tired of them you can pull them out and (probably) they won't come back. Plants with larger leaves are slower starters, usually. Try to see whatever plants you get growing in a tank so that you can see whether they're taking over the tank or are happily getting along with other plants. You really do not want an invasive species in your tank.
Not all plants get along well together. Some plants produce alleles that will all-but-kill other types of plants in a small, enclosed tank. Not that that's a bad thing (especially if they're death on invasive species, but then invasive species are invasive because they resist most forms of control). Alleles are the chemical warfare of the plant world. It's part of the process, so if some plants don't work, try others until you get a happy mix.
Fish: your choice. If you plan to keep Cichlids, then don't be surprised when they rearrange, by which I mean totally destroy, plants in your tank, push the gravel around, expose the soil, dirtying the water, then die from the turbidity and turgidity. Or, go with a community tank of inexpensive, but colorful fish. Or, whatever you want. Fish produce CO2, which plants need for respiration, and plants produce O2 which fish need for respiration. Don't worry about micromanaging the perfect symbiotic mix of plants and fish for the perfectly functioning tank. Only nature does ecosystems well, and your tank will balance itself quite well if you don't try to metaphorically push worms up straws.
And, if it doesn't work out, well, you can always try again, but I can pretty much guarantee that a functional and healthy planted tank will require less maintenance, less filter cleaning, less water changes, and less stress that a sterile fish-only tank that's always on the verge of self-destruction.
A word about pathogens. Any sick fish is either a sign of an unhealthy tank or was, more likely, sick when introduced into the tank. You're going to occasionally introduce ick, or some other disease. It happens.
I mentioned earlier that one of the things I like about cannister filters is their easy adaptation to adding a UV "filter." First, UV does not kill anything. It scrambles DNA and RNA and usually prevents organisms from reproducing, or if they do manage to reproduce, their progeny are usually sterile. UV does not kill pathogens. It will, however, alter free-floating algae and generally prevents "green-water" in tanks that have living plants.
But, to be effective, any living organism must pass through the UV radiation to be affected. This means that filamentous algae that lives on rocks, gravel, wood, or any other damned place it feels like it can't be controlled by UV. If your UV system is on the outflow of a cannister filter, any organism you want, or hope it will kill must pass through the filter system before it gets to the UV light. Many organisms are so tiny that they actually will pass through the UV light, so this is a good thing. But not organisms that live on rocks, gravel, plants, wood, fish, snails, shrimp, frogs, or whatever.
Likewise, any UV light that is immersed into a tank, or hangs from the side, inside of a tank, cannot possibly be very effective, can it? I mean, if it's light is potent enough to destroy the DNA of passing pathogens, then it should also scramble the DNA of any fist, snail, or invertebrate that gets that close too, right? I don't recall reading any warnings on any of those types of UV light warning that fish should be kept at least three inches away, so I have to assume that they only value they might possibly have would be in scrambling the DNA of anything dumb enough to actually live on the light, like, maybe algae. Save your money.
Increasingly, UV disinfectors are using LEDs instead of bulbs with fluorescing coatings, or which there are two main varieties: cheap and expensive. The cheap ones, it's claimed, don't really kill pathogens though they may kill water-borne algae. The expensive ones claim to kill all pathogens because they're more powerful, or more concentrated, or create more UV radiation. We're talking about $80 versus $300+. Is there, or do they have a point? Yes, and no.
In reality, the rules above still apply: To have its DNA scrambled, any organism must pass within millimeters of the UV source, so anything that clings to rocks, wood, or fish isn't likely to go through the UV radiation, and so, will be unaffected. Can you really sterilize an entire fish tank, let alone all of the organic and inert objects within it? No. Once a fish has a pathogen living in or on it, UV won't help. What about spores of pathogens? Well, if they pass the UV, maybe, but if they settle to the tank bottom, no.
The best way to protect fish from disease is to, first, not introduce diseased fish into the tank in the first place, and second, maintain a healthy tank - which means one with plants and a symbiotic, functioning ecosystem in place - and let the fish's own immune system protect it from disease.
Speaking of an ecosystem we read a lot about the hand-wringing accompanying the question of whether one can "engineer" a healthy ecosystem, and if so, how to go about doing so. I like to think that life is either self-balancing or self-destructing, depending on what it see as correct. If an ecosystem is out of balance it will either eventually become more unbalanced, in which case, speaking of a fish tank, for example, the fish and plants will begin to die off and there's not much you can do. Or, the system will balance itself out, the fish and plants will thrive, with the odd and occasional minor disaster or dead fish passing away due to old age, aggression by other fish, or whatever, and it will simply "work" without much human intervention. When a large fish dies, I usually notice it. But when small ones go, I don't necessarily see it, and the system cleans up its own messes without my help or intervention.
I like to use a pre-filter on my tanks, a porous cellulose filter that traps the big gunk and keeps it from clogging the main filter. If the gunk is edible, something will eat it; if not, it will disintegrate into constituent components and eventually pass into the filter where I presume it will be organically treated, or trapped. Water changes are about two to four times a year, as are filter cleanings. Once every year or two something seems to plug the filter up a bit and I'll notice that the stuff on the surface isn't going around in circles at its usual pace, and I'll clean the filter, often as not, failing to find the reason for its slowing down. Cleaned up, it's happily spinning water around again.
No bubbles that would upset the balance of O2 to CO2, no surface water turbulence that would do the same thing. An never, ever any charcoal that would remove all of that free plant food in the form of ammonia my fish happily produce as a part of their daily lives. Vacuum the bottom? There's nothing there to vacuum. Oh, and a happy plethora of trumpet snails that only come out at night to forage and clean up whatever it is that they eat. They maintain their own balance of snails-versus-snail food; I don't know how; I doubt they give it much thought either. They disappear with the light, crawling off into the dirt, or at least I assume they do, and I suspect they prevent anaerobic conditions from occurring in the soil. I don't know; they're not saying.
