Recommend urethane sealant for flags

[Purist]

Hi

I have recently had some new flags laid (about 6 metres square). They are not a particular expensive make, Bradstone I think.

The efflorescence has gone, only to be replaced with algae/moss.

Now, I'm a rather lazy person and I want to avoid future annual pressure sprays. So using a sealant to avoid future growth sounds a great idea.

Can anyone recommend a brand that is particularly good ? I have read - on this site - that urethane sealants are best?

[TheVictorianCobbleCo]

Chuckle. If you're going to go this route then a UV stabilized sealant is important, but from my experience most sealants need to be re-applied anywhere from 6 -18months, and dont assist in keeping the patio up to BBQ standard. I identify with your laziness, but I suggest a saturday/sunday morning, bright sunshine, a cold beer, stiff broom and warm soapy water, or a mild acid wash followed with clean water every 3 - 6months, autumn and spring means avoiding winter. Spray with a weedkiller after cleaning.