Possibly not- the caresheets I've seen indicate it likes thing a bit on the warmer side. I've always gone with the "chuck it in and see" school of planting, which has generally worked out for me. There's only one or two plants I'd really like to grow that I've never had much luck with.

Is there any reason why you couldn't run a protein skimmer on a FW tank?

If you're in Essex, chances are you'll have hard alkaline water, so you won't need to add any calcium tablets. Its worth checking your pH and hardness to be sure though. Anything over about 7ish should be OK to be honest.

For the tank some Java Fern, Java Moss, Willow Moss, a moss ball (possibly opened out and tied onto a bit of slate with some thin cotton), will all be fine. I don't know how powerful the light on the Edge is, the tank itself isn't terribly deep, and getting into it to do maintenance is awkward, so I'd go for slow-growing, low-light plants like those. The shape doesn't really suit floating plants either I'm afraid. I've just set up a 27L cube for Sakura Shrimp, and am going for ferns, mosses, and algae only, but that's a personal choice.

The algae-covered pebbles will be ideal. Mature filter media will be great- many people keep a bit of sponge in their filter that they can put into a small filter and set up a QT or hospital tank at short notice, you'll just need to feed the tank an ammonia source (either liquid ammonia or fish food) to keep the bacteria ticking over if you're not going to add shrimp immediately. (I kept mine in the other filter until I got the shrimp home, and then moved it over while I was acclimating them).

The Edge (and similar sized tanks) are ideal for small shrimp. Unfortunately there isn't a caresheet for any other than the (significantly larger) Amano Shrimp, but in general terms their needs are similar.

Neocaridina heteropoda (the species which Red Cherry Shrimp and the other colour morphs belong to) will happily breed in freshwater (which Amano's don't), get to about 2.5-3cm long, and are gregarious. If you're buying new I'd get five or six to start with (having fully cycled your tank first). They like a pH of between 7-8, and relatively hard, but to be honest they're pretty much indestructible, and will breed readily in most water conditions. If your water is very soft I'd add some limestone rocks or coral sand to buffer a bit, as they do need calcium for their exoskeletons.

If you have acidic and soft water then the more demanding Crystal Red or Crystal Black shrimp (Caridina cantonensis a different genus and species) might be worth a look. They're available in various grades, which are progressively more inbred and each requires more exacting water conditions. Red Cherries are ideal from that point of view, and even the "high grade" Cherries like Sakura Shrimp, are pretty tolerant. (They're also not nearly so expensive- Red Cherries go for about £2-£3 each, Sakuras are about £6, but the Crystal Shrimp come in at £15, and the really high-grade ones are silly money).

In a centrally heated house, and in a tank over about 100L I wouldn't bother with a heater, unless I knew there was a real cold snap coming, as the water volume will keep it warm enough, but in a 23L you'll need the heater as small volumes of water lose and gain heat much faster- set it to about 22-23 degrees and it'll probably only turn on when it gets really cold, but that will be when you need it most.

Being only small they don't need much food- a tiny pinch of finely powdered flake is fine, or a crumb of algae wafer once a day or so. If you have Java Moss (or similar) they'll pick through it looking for tiny bits of food, and its worth encouraging some algae growth on pebbles for them for similar reasons. Substrate isn't too important, but shrimp generally have more intense colouration on a darker substrate, and get washed out if your substrate and lighting is very bright. You should also give them places to hide (small flowerpots, pieces of wood, plants, etc), as shrimp are right at the bottom of the food-chain, and know it- especially when they're moulting and are even more vulnerable to predation.

The one thing you absolutely must avoid is copper in any form, as it will kill them stone dead. In a shrimp-only tank this is pretty easy to avoid as the most common source of copper in an aquarium is fish meds. A nerite snail or two, and a few Malaysian Trumpet Snails if you have sand, and you'll have a lovely little invertebrate community tank.

A bit of nibbling won't be a problem. It was getting lawnmowered from below by the American Flag Fish that did for it I think.

18W in a 60-100L should be fine for Water Sprite. Mine grew fine in a 60L with 11W. If it decides it wants to float (and it probably will try and send off floating bits) it'll be fine.

Amazon frogbit doesn't seem to mind what the temperature is, but it doesn't like being nibbled from below. Salvinia should be perfectly OK too. I wouldn't get duckweed other than the Ivy Leaved Duckweed as its too rampant (Ivy-Leaved duckweed doesn't float on the surface but just below). Water sprite can be grown either as a floater or rooted, and is found in the some of the sme localities as WCMMs are, so it would be biotope correct if that matters to you.

Either the 9W or the 11W would be fine then. While I bought the 11W, I think I prefer the shape of the 9W ArcPod. Its easier to work around and still illuminate the tank.

How big is the tank? The Arcadia ArcPod and Ellipse are very good, there's 9W, 11W, 18W, and 24W versions. The tank size will determine how big a light you'll need. I've used an 11W on a 30L and a 60L and that was more than adequate for the easier plants (moss, Java Fern, the less demanding stem plants, etc). If you started using a high tech set-up with CO2, and dosing fertilisers you may need the more powerful one. (They are bigger though, so a 24W tube might not fit over a small tank properly).

As long as the test-tube isn't sealed I don't think it will make any difference whether you use a glass or the test-tube.

Your GH and KH can usually be found on your water-board's website.

Thanks Fishadmin! It works!