week (£40). I'll try to make a good diffuser for it, ive got some
ideas that i will try out. Whats the best kind for getting co2 levels
up to 30ppm? I currently use a bell system but i figure this isnt the
best way when using a pressurised system. I have an internal power
filter with a venturi valve but might be convinced to get an external
cannister if it will prove easier. I wont be beaten by this BBA, not
at any cost!!

A simple powerhead bubbling the gas up into the impeller region will
dissolve well. There are a few ideas on the Krib as well.

Check your tap water by giving them a call and ask for the NO3 and the
PO4 levels delivered.

Ive got details from the water board, NO3 is between 30 and 50ppm,
depending on time of year (fertilisers running into our rivers etc)
and PO4 is about 0.5 ppm

Well, pass on the NO3 dosing for the water change but you will need a
dosing 1/2 way through the week. About the 3-4th day but that's all.
Same for the PO4. One dose a week about 3-4 days after the water
change.

That's based on a 50% weekly water change.
You might want to add a bit more PO4 around 2 days after the water
change and the 4th day.

I take it i should dose just the k2so4 and flourish and use the water
changes to add NO3 and PO4. I currently do a 33% water change weekly,
using the water filter to bring NO3 down to about 10ppm and remove PO4
completely. Should i do away with the filter and go with the 30ppm
NO3/.5ppm PO4?

Yes.
Why take it out then add it back again?
I think about 1/2 way, you'll run out of NO3 and after 1-2 days you'll
be out of PO4 doing a 50% weekly water change.
You'll still need to top off during the week.
K2SO4 definitely will be needed after the water change only. Traces
2-3x a week.

Is my lighting OK? 120 watts over 35 gallons. Thats about 3.5 wpg. I
take it that is fine. Maybe i should swap a couple of tubes for newer
ones, they are about 6 months old now. Whats the best tube to get?

Not sure over there. I like triton's for regular FL's tubes. I mix
with a cheap bulb from a hardware store.

Should i just be dosing Seachem Flourish or should i add some Leaf
Zone (just contains Iron and Potassium) daily (as Wayne does - i
think)

Either.
Regfards,
Tom Barr
I think thats all for now, thanks again for your help.

Mark