Eleocharis parvula / Microsorum pteropus narrow / Vallisneria spiralis 'Tiger' / Sagittaria subulata and spiky moss, is this a good mix of easy beginners plants? I would also like to have some form of floating plant but not sure which would best suit.
Given
these specs on the Roma 125 you might consider upgrading the lighting to T5 (ie unless you've the kit already look for the Juwel version with T5 lighting included ... one day Hagen/Fluval will run out of their stock of Glo tubes
) - with the higher light at substrate level your E parvula & S subulata will remain (usually) shorter
Although these are all "Easy" plants, they will nonetheless prefer some substrate nutrients so I'd suggest including
Tropica Growth Substrate layered beneath sand/fine gravel - once established these plants will invade even large gravel areas but during initial growth/transition most plants prefer finer substrates (I suspect this has to do with the localized microenvironment established around developing roots)
I suggest thoroughly investigating Tropica's website, they have a lot of great information that is presented very clearly (& succinctly) through word, photo & video ...
like ADA follow their "rules" for a successful planted tank, & that's pretty much what you will get (they are just a lot less complicated than ADA)
Tropica's 90 Day App is a well worth following.
Once you've got your first tank through it's first successfully grown in scape, then start playing with EI & other methodologies (if that's your inclination)
2. Also from the picture it doesn’t look like any special planting substrate was used, so my question is in a low tech tank with similar substrate and gravel would I be able to achieve a similar scape with no C02 or ferts.
Don't lose sight of the fact that these are Trade Exhibition Display Tanks, nothing has been grown in or is necessarily set up for this (some display booths such as Tropica & Juwel transport scapes that have been grown in for the Exhibitions, but as you may imagine this is a much more costly/complicated endeavour)
Plants must have means of life - in order to produce new leaf, stem, root, some sort of carbon source is needed (it's the "
backbone of life") as well as various macro & micro (trace) nutrients.
Tropica makes this easy by supplying substrate ("Growth Substrate" & now "Aquarium Soil" - you can just choose one), fertilizers & CO2 options
If you have more nutrient rich tap water, it's often possible to have slow growth without adding additional fertilizers (especially if there's a nutrient rich substrate - BUT this needs to be a balanced for aquarium life substrate, toss in a bunch of garden dirt/compost etc & you'll likely end up with a mix that is far too rich/excessive & algae soup is rather likely ... if you're keen on home sourced products, take the time to thoroughly research dirted tanks ... companies such as Tropica have spent considerable funds on the Research & Development & science of growing aquarium plants)
3. I would prefer to use black gravel / sand but would this make it look less natural
4. What colour form of rock should be used with black substrate
Most fish prefer dark substrates but there are very few natural "black" substrates (most look too glittery or dyed)
If you want a more natural look, then try to match rock colors with substrate ... OTOH a nice algae covering on rocks can soon obscure a lot of rock texture/color
There are many tanks set up with contrasting rock & substrate color/texture, once tank is grown in this seems to all come together
(note local shop has loads of Hagen "display" tanks but they are all supported & designed by the shop, not Hagen ... this year Hagen has finally upgraded the lighting in the Spec line of tanks so that planted scapes as shown on the displays & boxes are finally doable without modifying the stock lighting ... of course, there's also been a significant price increase as well
)