A few days ago I noticed the concrete starting to have a different darker shade to it. As you see in the photo. I watered it down and let it dry. But today I’m seeing these white blotches as well Does anyone know what that is and how to cure it? I have about 40 of these concrete steps and it’s just occurring at this section. We have a saltwater pool. could it be that? If so, why I would just happen there and not anywhere else? [img]https://cimg3.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/2f41df35_d31b_4f81_b1e5_2e0ef89b754f_6a0f70dc43e4c6f321f871e15a42ab499b3fe8c5.jpeg[/img] Hoping someone can tell me what’s going on and how to fix it. I don’t want to experiment with the wrong cleaning agent before I run it by some experts in the field. thanks!

Hi all. I wrote earlier in this week about an uneven brick patio that seemed to have 3/4" gravel under the bricks. [color=#222222]I did some digging and learned that there is a French drain under my patio...hence the gravel. The rest is sand over gravel as it should be.[/color] [color=#222222]The brick pavers use a running pattern parallel to the perforated black flex drain pipe.[/color] [color=#222222]I presume perforated pipe French drains hate sand (true?) and I know brick patios love sand.[/color] [color=#222222][b]Question 1:[/b] Can I get the sand any closer to the drain to make the brick leveling easier? I think the gravel bed is about 16-20" wide.[/color] [color=#222222][b]Question 2:[/b] The point of greatest subsidence was over that drain inlet. Is that supposed to be over a very slightly angled bowl in the bricks? Wondering if that makes a difference. It does seem, after 25 years, that there is not much of a bowl leading down toward it.[/color] [color=#222222]Thanks! [/color] [img]https://cimg5.ibsrv.net/gimg/www.doityourselft.com-vbulletin/320x240/img_5737_e0f2544486f25c93e768b09d7a8df972238a5556.jpg[/img] [i]You can see the perforated drain pipe, with a cleanout/drain at the lower center.[/i]