High pH in concrete pond  - 04/05/2006
I built a cement pond with cement from Home Depot. I sealed it with Thoroseal and had problems with the pH being 8.4. My pond shop suggested
that I add vinegar for a couple of months so I did that and washed the pond out. The pH is still too high. The local cement dealer looked up Thoroseal
information and suggested putting a 12% solution of salt in for one day.
<Mmm, salt won't help...>
This required 120 lbs salt but this did not work either. Do you have any suggestions?
<Yes... You could try a good/strength acid wash: http://wetwebmedia.com/PondSubWebIndex/acidblchpds.htm
and the linked files at top>
Can I paint a rubber or neoprene paint on top of the Thoroseal?
<You can/could>
If not, how do I get the Thoroseal off? It actually seems like the second coat of Thoroseal has come off on its own as it was a slightly different
color from the first and I can see that hardly any of it remains.
George Strang
<Can be chipped and acid-washed/etched away. Do pay close attention to the cautions/warning statements re this procedure. Might I ask what your intended use of this basin/pond is? It may well be that you'd be better off allowing "biological intervention" here to cure the high pH/alkalinity issue. Bob Fenner>

Pond construction... mainly 6/31/05
Just recently we added a cement pond to our back yard. And before putting water into the pond I need to know what measure should be taken to prevent leakage.
<...?>
A few question I have is how long should I allow the cement to cure before cleaning it with a solution? And what type of solution should I use?
Thanks for your help!
Diamondmind
<The basin/s shouldn't leak if they've been constructed properly... some folks seal concrete with a coating that aids in protecting the material and rendering it less likely to affect water chemistry. Most installers use an acid wash to reduce alkalinity... some people just utilize vinegar here, but professionals often dilute Muriatic (3M HCl) and brush this on, rinse, pump out... These issues are covered on WWM: http://www.wetwebmedia.com/PondSubWebIndex/Pond%20Sub%20Web.htm
You might avoid a good number of future issues by studying now... Bob Fenner>

Vegetable Oil... In a Pond?
Here's one for ya,
<Ho boy>
My step-son, in an attempt to prime a non-submersible pump went and poured a half of a bottle of vegetable oil in the hose per the manufacturer's instructions,
<What the?>
which is now in the pond. It's @ 500 gallon, 4" deep. I tried to skim off what I could with a pool skimmer net (which is now like paste) but it has coagulated into white clumps which is now on the bottom and covering the liner. Is there anyway short of draining and scrubbing with Dawn to get this out? Such as a natural biodegradable neutralizer or an 
aggressively large cooking oil eating fish?
James
<Thank goodness you have a sense of humor. For this size system, I would drain all (including plumbing, filter...) and use a detergent as you mention. Do take a read through our Pond subweb re plumbing, check-valves... arrange for this conduit to stay primed when the pump is off, out... and no more vegetable oil! Bob Fenner>