[Iain macdonald]

just bought my first drum hypo thought was about time i give it a try.the stuff they sold was Dairy Hypochlorite i take that just same stuff i got from farmers supplier.judge by what can see it say min 10% hypochloride what streghth do i mix this still 1-4.can it be used on a sealed drivway will strip the sealer off.got job to do that i sealed last year but they have problme with moss

[Smurf]

Sealed block pavers I found is a real breeze to clean just by using a decent cold pressure washer. Surface moss and grim should wash off very easaly so I would try that first as you should not need to use any hypo on it at all if the sealer is any good.

I'm also betting that they have never bothered to maintain it in that year either just by sweeping it and washing it down with soapy water. Then hosing it down to keep the sealed joints and surface clear and clean so moss spores etc doesn't start to grow back.  ,

You will soon know if you have sealed the joints properly between the block pavers by the amount of sand if any is removed during pressure washing.

To be blunt If you've done a realy crap sealing job then loads of sand will be removed so then it don't matter if you use hypo on it or not 

[BDCS]

The usual issue is that the lichen is sealed in - not cleaned properly in the first place

[Charlie Allen]

Im just wondering why you would think hypo would strip sealer..........? its bleach nothing else. Before buying and using products for h&s reasons at least spend a little time finding out what the chemical is and what it does! Don't believe everything you read on here
theres a lot of mis imformation