Inline (the bigger the better) are the only ones that are worthwhile. Its all about 'dwell time' and that depends on flow rate and the power output of the UV device and tank turnover values. Are they a sound investment for the planted tank, perhaps not due to low stocking levels of fish and high planting levels that are typical of most set ups.
Do I have UV, yes I have Vecton 600 units which are the smallest that I would buy. Are they running at the moment, no, but I hope to get them up and running by the winter.
Why Vecton, well I bought many years ago and they did have quarts sleeves and UV lamps and parts are available both from TMC and from other reliable sources. I assume that other quality suppliers now exist. If size and cost are not an issue look at units designed to disinfect drinking water supplies.
Be very wary of some suppliers, it may be 'lost in translation' but the UV tube has to be quarts and stamped with recognizable makers name as germicidal and the sleeves must be quarts. Glass used in cheap models absorbs UV, only quarts will do. What 'quarts glass' is I have no idea but I will not buy any thing so described.
With care only the UV lamp and sealing washers will need regular changing. Wash the sleeve will dilute hydrochloride acid or limescale remover and buy your UV replacement lamp/tube from a UK electrical component supplier from the net. The Vecton 600 unit takes industry standard lamps.
Sorry no cut and dried answer. Could be regarded as a 'faith issue' plenty in this fancy, some defended to the death.
Quartz glass is made from melting pure Quartz crystals so is or should be, having a silicon dioxide aka silica content of 99.9% compared to glass which has impurities in it so the silica content is less.
Thanks for the reply I might just leave it for the mo just ive seen some tanks and they ate not using them just thought algae being a scapers nightmare they would not take the risk and have them right from the get go ?