his problem isn't just the water... having that many plants I'd guess he's going for a near neutral ph
but he's in a constant fight between the turnover and the co2...
excess CO2 when used to correct ph for eg makes plants grow faster and thinner not stronger and thicker looking plants
as for people in england and soft-water...99% of the people from england I see here asking for help have hard-water but that isn't his main issue...it's turnover VS co2 in a constant fight
easiest trick you can do with planted tanks and CO2 (not aiming to control ph)
it's to drill a hole through the cap of a plastic bottle like a 750ml coca-cola bottle..attach some tubing to it...cut the bottom and and sink it by attaching a rock to it...
then when you turn on the co2 instead of using 1bps run it maybe 1 bubble per 10-15 seconds the reasoning for this is that
when the pressure rises by filling that bottle with co2 and push water down it'll stop the co2 tank from filling it up more..when the plants use the co2 it'll allow the water to rise inside the bottle
which in turn will cause the co2 tank to fill it up again
if the co2 is just for the plants and not to control any water parameters..this would be the most effective way for the plants and least cost expensive than using a diffuser and just letting co2 disperse at the surface
when it comes to flow...many people will suggest many different things...5x usually being that "sweet" spot
but as you spend time in this hobby and learn from others through time...you'll find that most often that not, almost everyone with high-turnovers are always fighting algae
be it in the substrate and weekly water-changes, on leafs, by overfeeding..the easiest way to decide what's a good flow for your tank is to just look at it...
set it up the way you want it..nozzles pointing here and there...and don't touch them because it'll affect how movement affects things inside the tank
then adjust the flow and after 2 weeks look at the nozzles and the intake to the filter which are the most flow affected areas...if you find yourself in a position where you have to constantly clean it every month from algae growing on the intakes then you know your flow is too high
now root tabs...I've heard people complain about different tabs that some won't feed their floaters/non-rooted plants
the way I think of it is simple...tabs will melt eventually in the substrate in around 2 weeks and the powder will stick to your substrate and some lose particles move nearby with the water movement
when you have fish that move the substrate they'll release some of it into the water column which will feed floaters and non-rooted plants with also fish poop being a fertilizer in the tank
small fish do better in these types of setups as they won't move the substrate too much like cories/hillstream loaches/otos or some type of dwarf pleco like L144 or L046
L144's will actually dig themselves into the soil which CAN in turn release some plants depending on how active and often they bury themselves where l46's are a bit smaller and don't have that same tendency although a bit more expensive fish
now if you're looking for fish a bit cheaper and that won't destroy things like a super-active L144 could
I would probably go with zebra otos instead of L144 they're a bit bigger than regular otos, some amano's as they won't breed and cause you to have a shrimp tank instead of a planted tank
and some cories...a big enough school (5/6 will do) not to be disturbed by the hillstream loaches as loaches will push cories around from their food
the tabs I use are called Thrive NA...
