• Yes, the vacuum dewatered concrete requires curing in order to gain its strength.
• The concrete is cured for 28 days.

we dont know, thats why we asking you

The Vacuum Dewatered Flooring or VDF Flooring is a system for laying high quality concrete floors where the key is Dewatering of Concrete by Vacuum Process wherein surplus water from the concrete is removed immediately after placing and vibration, thereby reducing the water: cement ratio to the optimum level.

Apply vacuum test to the booster. If it does not hold vacuum it is defective. You can borrow a vacuum gage at most auto parts stores.

You could go lazy man's style and just take the vacuum line off of booster. If the brakes are as hard as concrete, then put it back on and the pedal is smooth, you got yourself a decent working unit.

Black algae is very tough, it sends roots into the concrete of concrete pools. before bombing it with strong algaecide destroy as much of it as you can with an steel or copper brush and vacuum the remains to waste the next day when the water has settled down. You are better of not letting the stuff into your filter as it may may reappear if it not entirely dead.