Hello, again! Once I learn more about water keeping and fish keeping, I would like to have a planted Discus tank. Honestly, this will most likely be 1-2 years away. But, I realize that setting up a large, planted aquarium can be costly, so I want to start planning now. My goal is to have an 85-100 gallon aquarium. Can anyone tell me what items I should prepare to purchase for a planted Discus tank (besides the tank itself)? I know I will need to plan for:
the tank itself
substrate
heater
plants
mopani/bogwood
fish
some sort of filter (not sure what kind would be best & advice on this subject would help)
water conditioner
food
veggie clip
Will I need a CO2 Injection System and/or an RO Unit? Is there anything else that I should plan for? Thank you again for your help! Our 37 gallon aquarium cost us over 500 USD. Usually, I am good about research, but I really missed the mark on this (I thought it would be about $300 for everything). So, I want to be more prepared next time.
First off, keep in mind that discus tanks are very difficult to maintain, and not for the novice fish enthusiast. I realize you are thinking a year or two off, but I just want you to realize what you would be getting yourself into. If there are "mount everest"-like challenges in the world of tropical fish-keeping, this would be one of them. That isn't to say you couldn't do it, but you have to be prepared to put in the level of care that would be required. (daily monitoring of water parameters, weekly or bi-weekly water changes, etc.) I would estimate that the level of care required for discus is fairly close to that of a reef tank.
Also keep in mind that you have two different "issues" here. The first is keeping a planted tank, and all that entails. The second is keeping a discus tank. I don't think you want to be learning what is required for both at the very same time, so I would spend a significant amount of time keeping a planted tank, or keeping your eventual discus tank as a planted tank. Once you have the hang of that, then go on to discus.
That being said, a planted tank is an ideal place for Discus. Not only do the plants act as a natural filter, but they also tend to bring the coloring of the discus to a maximum, so the tank looks really spectacular.
As for size, I would opt for a larger tank (like 80-100 gallons) for a couple reasons. 1) Discus can grow quite large (some as large as 10-12 inches), and they do better in larger groups (six or eight). This limits your options to larger tanks. 2) A larger tank will tend to experience water chemistry changes and temperature changes much slower than a smaller tank, and discus are very fragile when it comes to water chemistry. A larger tank would lessen the chance that a change in water chemistry becomes a major issue and results in a catastrophic (and costly!) loss of your tank stock. Obviously a larger tank is more expensive.
As I just mentioned, discus are pretty expensive. Your best bet is to find a reputable breeder in your area and buy from them. Not only might they cut you a deal, but you have a better chance of the fish living the first few hours or days. Online sites might seem like a good idea - but discus simply do not do well with large amounts of stress, and the shipping alone might be enough to push one or all of them over the edge. You can do it, but don't say I didn't tell you it's a gamble. In any case, you are looking at spending 20-40 dollars per fish as a minimum (this would be a good price and a small fish), but more like 40-80 dollars. And they need to be kept in groups, so multiply those numbers by four to six, minimum.
Filtration, C02, substrate and water conditioner: I've grouped these because, as a I mentioned at the beginning of this response, you have two issues here: planted and discus.
Filtration is a bit different in a planted tank: 1) You don't want the filter too much of the "bad stuff" because that bad stuff is actually food for the plants. 2) you don't want the filter to mess with your root system and/or co2 and 3) your less concerned with chemical/biological filtration inside your filter because that job is being done by the plants. Thus, your best bet would be a canister filter with the media removed, or a hang on the back filter with no bio-wheel and the water level in the tank as high as possible. (the spalshing effect of a HOB filter creates water disturbance which drives off beneficial c02) You definitely don't want an under-gravel filter because that would most definitely screw with your root system and become a giant mess. The end result in a heavily planted tank with a simple mechanical filter would be a very stable tank. Keep in mind, however, that it takes some time to reach this stage. The tanks need to root well, start growing (with the appropriate levels of co2 and light) and basically get settled. Only then will they start to do the job your filter was doing before. Only then would you be able to introduce a fish as sensitive as discus. This isn't hard to achieve, it just takes time (a month or two). The actual filter would be no more expensive for you then an unplanted tank, but you would have to pay for the plants (and they can be pretty pricey).
CO2: You would have to have injection. First, it is tough to keep the c02 levels in a larger tank (say, roughly greater than 50 USG) at any consistent, elevated level with DIY fermentation. Second, DIY systems fluctuate wildly in the level of co2 they provide due to slow downs and speed ups in the fermentation process, and the ulreliabiltiy of bubble production/absorbption). This would wreak havoc on your ph, and, as we discussed earlier, discus don't handle change well. You would need pressurized injection, which would run you several hundrend dollars.
Substrate: have to get or make a substrate that works for plants. There are a lot of options out there, but you have to make sure it is one that is not going to change water chemistry too much. (things like peat moss will definitely do that). If you made your own using something like, say, play sand and laterite you probably wouldn't spend more than 5-10 dollars per twenty pounds. (don't quote me on that though). On the more expensive side is something like Flourite, Eco-Complete, or Onyx. Personally, I use Flourite Red in one tank and Onyx in the other. They are expensive (approx. 20 dollars per bag), but they are easy to use, look nice and easy to plant in. Thats up to you, but I would estimate that in a 100 gallon tank you would need 10-14 bags of 17.5 lb Onyx sand, depending on depth you want. I'll let you do the math.
Water conditioner: Again an issue with planted tanks. If the water conditioner only takes out chlorine and chloramine then I'd say your fine using it to conditioner new water during a change. If its something like Amquel + that also takes out the big bad three (Ammonia, nitrate and nitrite) I would say no good, because it would remove stuff your plants need to survive. Personally, I wouldn't want to put chlorinated water into a discus tank no matter how small the water change (asking for trouble), so I would go with the former.
Lighting: You didn't have this in your list, but its a big deal. If you want good growth and a variety of plant options you need lots of light and c02 injection. You could go low tech, but you'd be restricted to under 10 types of plants that you could keep. You wouldn't need high lighting or co2 injection. This is an option, but truthfully if you want the good filtering effects that would be necessary for discus, then you need constant growth, and that requires high light and co2.
I won't get too into lighting here, because it opens a whole new can of worms regarding what type of plants you want, what kind of fixture you would want in terms of appearance (shop lights can work, but you wouldn't really want them in your living room over a show tank, so keep that in mind.) You can find this info all over the web if you google planted tanks. There are also some good threads here on the issue. Check them out and see what you think. Lighting is generally the most expensive part of the planted tank - simply by virtue of the fact that you want to fit an almost ridiculous wattage over a small physical area in order to be successful. It is essential though, and there isn't a way around it.
Finally, the last small issues:
Heater: don't need anything too special, but Discus require very specific temps that are higher than other FW Trops. For a tank that large I would buy several lower watt heaters that are pretty reliable, that way if one went out you wouldn't lose the whole crew.
Food: Discus have special food requires. Flakes: They sell it at the LFS. Its not hard. Don't know how expensive it is. Other: will also need frozen and live supplements. A website devoted to discus could tell you more.
Bogwood: go ahead and buy it, but be sure to soak it for a long time to remove any tannins that might leach into the water. But do buy it, don't collect it. You don't want to run the risk of getting something that isn't a true bog-wood. Also, bog-wood is pretty expensive, so keep that in mind.
I feel like an RO unit would be good for discus, but not great for planted tanks. I don't, however, have anything to back that up with other than my own personal hunch. Please check with someone more knowledgeable regarding that.
A few final notes: Keep in mind that Discus scare easily, so you don't want plants you have to trim every day. Having written all this down, I feel like you are looking at well over a grand to set this up, but you'll need to research each piece to determine the actual price. I could be way off. Finally, after reading this please think if you really want to do this. I'd try other options for a few years until you really get your feet wet (oh what a horrible pun, why would you want water on the floor?). Discus are for the advanced fishkeeper - and you stand to lose a lot of money and time if something goes wrong.
Anway, hope this helps! As always, if someone out there knows something I said to be false please post it so we can all learn something.
cheers,
mike
Wow, Mike! Thank you for the extremely thorough and helpful response. This is exactly the information that I needed to know. And, I especially like your idea of setting up a planted tank first, and adding Discus later down the road once I master the planted tank part. I think this would be a good idea for me since I don't have experience with either. 
We don't have any retailers of mopani wood, so I had to have it shipped from Texas. I guess I should plan on spending $100-$200 for bogwood and mopani wood. 
