PSI recommendations for pool patio and flat work

I have researched flat concrete work specifically for psi recommendations but have not adequately answered my question. I am going to be cleaning this pool. The concrete is over 2 years old (to my knowledge, will verify prior to work) but has these plastic divider and drainage “separators”. This is my plan. To pretreat with 1.5% SH application downstreamed. Surface cleaner is currently running two 25025 tips with a 4/4 machine which is yielding 2500psi. Post treat with 3.5% solution via 12v system.

How do you avoid damage to the plastic: Fan tip/turbo and edge all the plastic areas or drop the psi on SC? If changing tips, 25035 would drop my psi to about 1250 but keep flow. Is that enough, what is a safe psi to not damage plastic or run the risk of (ever) etching the concrete? I have used present set up on sidewalks and it either mars these foam like “separators” in the concrete or completely blows them out if they are old (my own sidewalk practice - no worries :wink:). I have the same question there. Edge or drop psi? Closest thing I have seen is just observation of guys running 8 gpm SC’s with about 1500 psi. While that’s awesome, the 8 gpm’s not happening anytime soon and I know it is the psi that is damaging, not flow. Thanks everyone for all your advice.

Don’t waste your time with a 1.5%. 50/50 mix in a pump up sprayer and hit the edges of the plastic and light pressure to edge, face wand downwards. Surface clean the rest.


@MuscleMyHustle, so you would pretreat with a 6% solution and then wash. “Light pressure” around the plastic meaning ? rinse tip on my j-rod which would be 2510 and 650 psi) but without any post treatment. I will use my 12v for any thing above 1.5%. It is a relatively large pool at a retreat. The build is on the way and I am doing a batch system based on @racer single axle rig. You would leave the SC pressure at 2500?

Thinking about the application to the black mold and agree the 1.5% isn’t strong enough to pretreat and wasting time. I have read multiple threads recommending post treatment for the most lasting effects. This a friend’s retreat in VA that I am blessing. Not close to me, so I want it to last. Pre-treat at 3-4% and post-treat at 3-4% would do little to change the quantity of SH to your recommendation but be effective to kill the black mold on both sides of the wash. Thoughts?

Your turning a basic job into a massive project here. What I’m saying is pre treat with 50/50 maybe 2 feet from either side of the plastic and finish the rest off with a surface cleaner, 2500 is plenty for
concrete. The less time you spend around the the plastic with a surface cleaner or high pressure the more assuring it is for you to not rip a piece out. Picture the plastic as curbing and the rest will just make sense. How much pressure to use with a wand is a feel thing I can’t really explain to you the amount of necessary psi. Build a proportioner system, batch mixing is obsolete.

Now I understand what your are saying regarding the plastic and I appreciate your input here and in all the other threads I’ve read. I know 2500 is plenty, I am worried about too much.

If I showed you the space on my truck that I am using (5.5’ Ford bed) and the skid I am making) you would laugh but we all are starting somewhere. Thanks to this forum, members like yourself, and the advice that I have received and what I’ve read, I know it will be effective. That’s all I really care about at this point. Would love to drop the extra $4500 on trailer, tanks and proportioner but it isn’t happening right now until cash flow develops. I can’t risk out family’s livelihood as times have become a lot leaner. Thanks again @MuscleMyHustle!

Are other people running their SC’s at 2500 psi or have you dropped it down via tips to prevent etching?

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You’ll be fine with 2500 psi.

Skids dont have to be amazing things as long as everything is safely secured, functional and reliable it’s as good as a 15k skid, it’s machinery at the end of the day that has a life cycle, wear it out and replace it as you go along and grow. Generally speaking 2500-3000 psi is the norm for surface cleaning, I wouldn’t lose sleep over a couple hundred psi, chemicals make up for that.

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Thank you both! I was doing a sidewalk and noticed it just wasn’t cleaning like it should. For some reason the unloader was openned which decreased my psi/flow/?both and really decreased the cleaning capacity. I don’t touch the unloader anymore. Tips, tips, tips.

I use a 4 nozzle Ultra Clean with 25025’s that yield 2500 at the end of 200’ of hose. Works very well on just about everything, there are times that a little extra PSI would help on aggregate.

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