i haven't had an issue in my 1 gallon bowl with a 0.5" cap of play sand, but yes in a larger tank i'll likely go more. I will stay away from dirt from my yard because i have no idea what kind of stuff is in there. I prefer miracle gro organic potting soil
Miracle-Gro Organic Choice Potting Mix – 16 Quart « IM-Hydro.com and will probably use that.
play sand probably has a nice tan color and different texture than the more whiter sands. i think i like it more. cleaning isn't that much of an issue i hope. in worst case, I'll have it sitting in a bucket with water running through it to rinse it for a while.
I was planning on keeping this very basic (having already been through all the artistic moves with iwagumi rocks, slopes, carpet plants, driftwood). I can now appreciate something very simple, so i have decided to go with just about one species of plant - blyxa japonica- but if i can find another species of blyxa for variety, i'll also include that in my scape. I hope to also keep maintenance to a minimum so i wont use any stem plants (other than blyxa, and i wont house any tall varieties either). Floating plants are a must, so i will likely use Salvinia or something similar.
Since the tank is only planned to have shrimp, I'll go light with filtration - probably one AquaClear50 HOB. just enough to supply water movement over the large tank. shrimp and plants dont need that much anyway. That should allow me to keep 300+ shrimp in there comfortably.
The scape will be very basic and probably not very showy like Amano tanks lol, but I'll try my best to make it pleasant to look at - the tank will be mostly just for breeding shrimp. the plants are an added benefit for biological filtration. The scape will consist of one large slope/hill, highest point somewhere in the middle of the tank, but probably off-center to try and follow the golden rule/ratio of scaping. Since I'll put soil in a big pile only in the center of the tank, (the outer edges will just have sand and won't be planted) the blyxa will all be planted in one big, elongated island in the center of the tank to provide cover for the shrimp. I don't know if i'll use DW yet, but i might use some on the outer edges to mark the boundary between the open sand area and the blyxa "island".
I'm still hung up on my lighting situation. I want this setup to be extremely low energy. It probably wont even have a heater (If i find that i can keep the apartment temperature at least 70F, that will be good enough). I'm thinking my light will just be one BoostLED PAR30 lamp, but i'm doubting that it could cover the tank well...though i only really need it to cover the center where the plants are, so it may work with just one bulb. the bulb is only 10W of LED, but it has decent light output, and if i put it high up enough, it might be able to cover the exact area i need; the outer edges of the tank don't really need much light since nothing will be growing there.
An LED lamp doesn't need to be replaced as frequently as other lighting, so that should help save costs even more. the lamp will likely last me more than 10 years without any worry, unless i drop it lol... so in total that would include the AC70 HOB (6W) and the light bulb (10W) so a 40 gallon running on only 16W would probably not be very expensive, providing the shrimp breed to great proportions and I will be able to sell them for a decent profit.
Add to that reduced maintenance: I want to steer away from doing much water changing in the tank. i feel the plants would really help with this, plus shrimp sucking out minerals from the initial water can be mediated by putting in a few mineral rocks in there for them...So i can likely end up with a tank that will only really need top offs, and very rare water changes if things get out of control with nitrates. Of course I'll still need to feed the shrimp once their numbers rise past the level that the plants can support (shrimp can find food all over the tank, but especially the bio film on plants and DW/substrate).
Finally to answer your actual question, I'll likely start out with my red cherry shrimp and see how they do. If they breed out of control, and I sell enough to make around $200+ then I will probably switch to a more interesting shrimp like sulawesi, but this shrimp choice will all depend on my tap water, which i will test once i move to the apartment I'll be living at. Most likely in NJ it's still going to be liquid rock though
which would restrict me to Neocaridina shrimp for starters and sulawesi shrimp as the most advanced shrimp i can get. If my tap is soft however, I'll likely go with crystal shrimp after i breed the cherries. And if regular red or black crystals are really successful (they are more expensive than most cherries too) then i could potentially look forward to getting some of the more expensive crystal shrimp such as Blue Bolt, Panda, Black King Kong, or Red Wine shrimp. Or i could just go with Tiger shrimp instead of crystal shrimp, eventually working my way up to Orange Eye Blue Tiger shrimp or Black Tiger shrimp. those two are the more expensive of that species.
At the moment I have some Taiwan Fire Red cherry shrimp growing up in one of my small tanks, so if I can manage to hold their population until i move and finally setup this 40 gallon beast, I'll be starting the 40 gal with them. I'm looking forward to being able to breed them for the most intense red I can get, because i think those really red cherries look best
They can sell for up to $9 per shrimp too. But I'm probably far from that point still haha.
In my other small planted tank, right now I have low grade crystal red shrimp, so I may be using them after my cherries are successful, but only if my tap water turns out to be soft...(I am using re-mineralized RO water for them at the moment).
Hopefully my rant about my planned tank helped your thinking about shrimp tanks, its even better if you think that some of my plans wont work because then we can discuss and find out what will work for either of our shrimp tanks. I wrote all that to try give you some ideas about yours too