question for diy rock makers

[dabandit]

DIY rock. Im a mason of 14 years its been my experience that cement that stays constantly wet over time will produce effloresence a white mineral deposit. Has anyone noticed this in their diy rock?

[dabandit]

When we do masonry around wet situations we use hydraulic cement because it doesnt contain gypsum,i've used hydraulic in ponds with sucess but im not sure how it would affect a reef. In researching recipes i;ve found no one uses hydraulic. Ok anyway......non hydraulic cement due to the high gypsum content is prone to effloress which is actually basically salt leeching out,now mixing the cement with rock salt then placing it in a marine environment in theory should make this worse. I would love to make some,but first I'd like to hear from users of this diy product to see if a;your salinity is rising or b youve noticed a white buildup on your rock or c if anyone has used hydraulic cement in a reef tank

[i have crabs]

i think people only use the portland cement cant remember which one but it needs to cure a long time before using it which makes it not really worth it to me unless you want a specific shape or cave mabey

[dabandit]

i've heard of people using type2 and gu (portland) but type 10hydro is the hydraulic and its needs the antihydro additive mixed into it.

Any experiences you've had with any type would be appreciated,I suspect because its underwater maybe the buildup wont occur?but might raise salinity slightlly as the minerals leech from the cement,maybe im thinking too much into this....

[i have crabs]

ive always read that the issue with cement rocks was thay affect ph quite a bit for the first few months i think garf.org has a bunch of info also i think talkingreef.com did a show or 2 about it.

[argan]

i've used regular type 2 in all my rocks and as long as i freshwater cured them, haven't had any deposits or salinity problems. Lots of coralline growth on them now tho if that counts as a deposit :P