Pressure Cleaning & Sealing Exposed Aggregate in South Perth, With Vacuum Recovery Around a Pool

Man pressure cleaning with surface cleaner on concrete
Pressure cleaning without water recovery, at the front of the property.

The more of these posts I write, the more I’m starting to realise how many great jobs we’ve missed out on taking sufficient photos for.

This was a very time-constrained job, so photos were a low priority compared to getting the job done expediently for the client. Our client rang on a Tuesday, saying that they were having a wake on that Saturday and not only needed the place to look excellent, but the pool needed to be pristine too. Fortunately, we had a very understanding client booked in for that Thursday, who graciously rescheduled for the following week, allowing us to take on the job. We typically wouldn’t ask someone to reschedule, but are happy to look into options as a wake is such a stressful event.

This was a beautifully decorative exposed aggregate concrete that was suffering from dirt and growth, causing it to look dull. Exposed agg is very porous, so this is quite a common occurrence when it is not sealed.

There’s two common methods of waste water recovery for pressure cleaning. The first is using an industrial wet vacuum, either attached to a special surface cleaner or stand-alone with a second operator and the second is to use a surface cleaner that has an in-built Venturi that uses a pressure differential to self-expel waste water down a hose. The limit with Venturi based systems is that they typically are limited to about 10m of hose to remain effective. Also, they only work while you’re using the surface cleaner and not when you’re using a lance, which will typically be around the edges, where the most dirt is being created.

We don’t specialise in water recovery and would do less than 10 jobs per year requiring it. Because of this, we haven’t invested in surface cleaners designed for recovery, particularly as they are often smaller than their standard counterparts. What we do instead, is cross hire an industrial wet vacuum from another company and have a second operator with a stand-alone attachment. It creates quite the complicated dance as we have multiple hoses, going in different directions, but it gets the job done well.

As you can see in the middle image, we use bunding to channel the water away from the edges of the pool while we vacuum it. We’ve made the bunding from flat hose filled with water. Admittedly, it’s a bit of an ugly solution, but it works well and that’s what we care about.

Pool surrounded by exposed aggregate concrete
Bunding around pool, to prevent waste water ingress.

Now, we love a good chemical treatment, particularly on exposed agg which as mentioned, is porous and the dirt and growth can be quite deep. And while we use chemicals that are largely pool friendly, we had to be extra careful on this one as even one day of being cloudy, could be a problem. Because of this we used our standard pre-treatment which is Sodium Hypochlorite and Potassium Hydroxide, but as a weaker solution compared to normal. We then Augmented it with additional Sodium Hypochlorite, which is pool chlorine. Ideally, no chemicals would make it past the bunding and vacuum and into the pool anyway, but we always approach jobs from a view of prevention, rather than remediation.

Other than the water recovery and pool friendly chemicals, it was a very straight forward job. We gave it a good pre-treatment, high pressure wash and a post-treatment to bring back as much brilliance and colour as possible.

The client hired us to seal the concrete as well. We only use penetrating sealers at Perth Pressure Cleaning, but it is worth noting that even if we offered coating sealers, it would simply be far too dangerous around a pool as it creates a slip hazard. Even with an anti-slip additive, we feel that it would be too great a risk.

Being a larger job, at approximately 250sqm, a Fluoropolymer sealer would have been a huge outlay. Instead what we did was use the Fluoropolymer sealer in food and cooking areas for it’s enhanced stain and oil resistance and in a couple of areas that were frequently shaded and subject to damp weather, for the best growth resistance. We then sealed the remaining areas with a more budget friendly Silane/Siloxane sealer.

vacuum hoses around pool