Re: Blasting limescale off my pool walls ?
OK, as nobody could give me any first-hand advice, I worked methodically through the problem. Firstly, here are some pictures of the pool BEFORE I got started:
My goal was to remove the limescale deposits by bead blasting without damaging my pool surface, and to do the whole project for under $300 (the minimum cost for having a professional do the job around here). Here is what I did:
Step 1) I went to Harbor Freight and bought the items shown in the pictures below. Total cost was $268 and change.
Yes, I know Harbor Freight stuff is made in China down to a price, but I've had good luck with their products in light-duty, infrequent-use applications, and it was about the only place I was going to get the required equipment within my budget.
Step 2) I used the submersible pump to drain the water from the pool. I placed the pump at the lowest point of the pool, next to the drain, and left it running overnight, pumping to the municipal drain at the front of my house via a regular garden hosepipe.
I got most, but not all the water out.
Step 3) I set up the blasting equipment per the sparse instructions, placed the glass beads in the hopper, set the compressor output regulator to 50psi, donned my protective goggles/gloves/facemask, and started blasting
.
The pictures below show the work in progress, and clearly illustrate the difference between the blasted and unblasted regions. At 50psi, I saw no damage to the pool surface.
Step 4) After blasting the entire circumference of the pool, I used a household broom and dustpan to sweep up as much of the glass bead residue as I could, and dumped it into a bucket for later disposal. I then refilled the pool with fresh water and allowed the pool vac (Hayward Navigator) to remove the remaining glass beads (which have the appearance and feel of sugar sand).
The photos below show the pool after blasting - a considerable improvement !
The tiles are now totally scale-free, but the PebbleTec still has some discoloration. The scale was easy to remove from the cement surface, but much harder to remove entirely from the pebbles (not sure why). I was reluctant to be more aggressive for fear of damaging the surface. My recollection is that the professional that bead blasted my pool some years back had the same problem, and the surface was not perfect then either, so I am happy with this result.
This whole project took over my weekend. Would I do it again ? ABSOLUTELY !!! Its always more satisfying to do this kind of project, to learn from it, and to be self-sufficient in the future. However, with 20:20 hindsight I would make a few changes:
a) The submersible pump I chose was rated for 1400gph, so should have drained my 13,000 gal pool in about 9 hours - in fact, it took about 36 hours. I'm guessing this is because of the long distance the water was pumped through a 3/4" garden hosepipe to the drain. Next time I would get a pump with a higher flow rate, and a bigger hose :lol: .
b) The compressor I bought was inadequate. Although rated for 6gpm at 40psi (the blaster only needs 3.2gpm at 50psi), this compressor could not keep up at all. If I tried to blast continuously, the compressor overheated and cut out. In the end, I had to blast about 3 linear feet of pool wall, then wait about 5 minutes for the compressor to cool off. Either buy a bigger compressor, or rent one.
c) The 50lb bag of glass beads was not enough. I had to scoop up, clean and recycle some to complete the job. The recycled beads did not seem as effective. Next time I would just buy 100lbs of beads.
d) An N95 mask and goggles are not adequate protection. Those glass beads get EVERYWHERE. Some got inside my goggles, and I was even feeling grit between my teeth for a few days afterwards. Next time I would buy a cheap sand blasting hood.
e) If you are doing this in AZ, watch out for scorpions hiding under the pool rim. Bead blasting them only makes them angry :grrrr: .
f) The Hayward Navigator pool vac does not like glass beads. The beads are fine enough to get inside the rotor bearings and cause them to grind/jam. I limped through the cleanup, but next time I will be more diligent about removing the beads completely before using the pool vac.
I hope you guys find the story of my adventure interesting, informative and helpful. If you have any questions, let me know.
Keeping the formation of the scale to a minimum via proper chemistry and tackling it early will prevent having to buy expensive blasting equipment and keep the blasted glass beads out of the pool :-D
