The Ultimate DIY Rocks!

[Rhodophyta]

Sugar? This site mentions something about the effects of sugar on concrete. The setting process is arrested, so the sugar would creat bigger voids than its pieces. the unset concrete would hve to be rinsed out. http://www.reefball.com/reef.htm Rice Crispies are also mentioned as a way to add voids to the concrete and sugar is a big cereal ingedient but it may not have as much of an effect being diluted.

 

[Insane Reefer]

Welcome to the thread Reno

Rhody, funny you should mention cereal, I was contemplating Puffed Wheat, which is mostly natural, and at a second rate grocery store, you can get huge bags for like $2. Was going to get a bag in the near future. Rice Krispies are some of the "low sugar" cereals, so I really doubt that the sugar thing would even be an issue - no more an issue that is, than adding any organic to cement would create anyway, which is a little icky sometimes, but not bad, usually.

 

[Nammy]

Not worried about the time to cure using something that will decompose. I sure some will be trapped inside the rock. Not all of it can get out. Just a question..

 

[blakeoe]

how would you guys prepare your rock for the tank after curing in a freshwater stream? I'm taking my rocks out of the stream today. They have been in for a month and a half and before that they were in rubbermaid tubs for 3 months. I was thinking about pressure washing them then soaking them in a bleach/water mix over night, letting them dry for a day or two then putting them in the tank. What do you guys think? Any suggestions?

 

[Rhodophyta]

<a href=showthread.php?s=&postid=9322764#post9322764 target=_blank>Originally posted</a> by blakeoe
how would you guys prepare your rock for the tank after curing in a freshwater stream? I'm taking my rocks out of the stream today. They have been in for a month and a half and before that they were in rubbermaid tubs for 3 months. I was thinking about pressure washing them then soaking them in a bleach/water mix over night, letting them dry for a day or two then putting them in the tank. What do you guys think? Any suggestions?

Rather than using bleach which would then be locked into the rock, I'd use hydrogen peroxide poured over the rocks in a tub. leave plenty of room for foaming up and then top off to the top of the rockwork with water and let sit for a couple hours.

 

[Insane Reefer]

I'd take them by the carwash, and use the "RInse Only" setting and blow them out.

I really wouldn't worry about any other measures - especially not bleach - I'd spray with muriatic acid before I'd use bleach. Anything "alive" in the rock currently will not survive the change to saltwater. I'd just blow them out, let them air dry for a few days, and then put them in, if they are finished kuring that is.

Post a pic once you have them in the tank

 

[Barto]

after the pressure wash, I would think a soak for a few days in tank change water to check & verify ph stability to be a good idea
(assure that the kure is done)

 

[speckled trout]

I soak mine in FW(a river). After 3 months, I remove them and pressure wash them to help resstore a little of their color and remove any grime that might have built up. Since I've never been a hurry, mine have always dried out for awhile before I placed them in my tank. Remember, whatever is "alive" in the them(bacteria) isn't going to survive the switch to SW anyways. I'd rather have them decay outside the tank!

 

[GuySmilie]

I contacted Quikrete and here is their response

I contacted Quikrete and here is their response

I wrote to Quikrete the other day, discussing the pH problems everyone is experiencing using Portland cement. I also told him about my theory of using their Concrete Acrylic Fortifier, to sort of do a 'molecular bond' with the lime, thus entrapping it within the stone. He wasn't all that thrilled with that theory. Anyway, here is his reply:

"The high pH leachate is part of the natural concrete hardening process. It will be most effective to allow the concrete to cure in moist (not under water) environment for 28 days and then to use water to leach the CaOH high pH material out. Leaching the concrete sooner - shortly after hardening (3-10 days) could - weaken the outer layer - though it is not likely to have a big effect. You can leach the high pH by repeatedly soaking overnight in fresh water - or submersing in running water. Naturally you do not want to pollute a small natural stream with large pieces of concrete."

"The acrylic will have some beneficial effect on reducing leaching of CaOH high pH - but not a great effect. There is no special problem with the acrylic fortifier in a marine environment."

Looks like there is no easy trick way around the month-long cure!
Guy

 

[Rhodophyta]

Re: I contacted Quikrete and here is their response

Re: I contacted Quikrete and here is their response

<a href=showthread.php?s=&postid=9343612#post9343612 target=_blank>Originally posted</a> by GuySmilie
I wrote to Quikrete the other day, discussing the pH problems everyone is experiencing using Portland cement. I also told him about my theory of using their Concrete Acrylic Fortifier, to sort of do a 'molecular bond' with the lime, thus entrapping it within the stone. He wasn't all that thrilled with that theory. Anyway, here is his reply:

"The high pH leachate is part of the natural concrete hardening process. It will be most effective to allow the concrete to cure in moist (not under water) environment for 28 days and then to use water to leach the CaOH high pH material out. Leaching the concrete sooner - shortly after hardening (3-10 days) could - weaken the outer layer - though it is not likely to have a big effect. You can leach the high pH by repeatedly soaking overnight in fresh water - or submersing in running water. Naturally you do not want to pollute a small natural stream with large pieces of concrete."

"The acrylic will have some beneficial effect on reducing leaching of CaOH high pH - but not a great effect. There is no special problem with the acrylic fortifier in a marine environment."

Looks like there is no easy trick way around the month-long cure!
Guy

One reason I use the fortifier is that I can use a thinner layer and count on it to have enough strength. If I use half as much concrete to make a structure, plus the fortifier has some small effect on leaching, then I have less than half as much leachate to worry about. Another reason is that the fortifier will allow me to produce much finer detail in the concrete surface than I could without it.

Letting the concrete cure for about a month before submerging it is a good practice. The more of the calcium compounds that have cured, hydrated, become part of the rock, the fewer there will be free to leach out.

I have not used a creek or the toilet tank, but a big plastic vat filled with rain water and handfulls of oak leaves to leach the rocks.

 

[Insane Reefer]

Whyfore the oak leaves?

 

[impur]

lol i assume they just fell into the tub. I plan to do the same thing, plastic tub outside on my patio and let the rain refill it.

 

[Barto]

I was assuming that there was a reason for the oak leaves, tannic(?) acid or some other naturally occuring compound that could have some potential benefit.

 

[Kurt03]

yea, i think the leaves help lower the ph?

 

[ebe]

I have always used the crushed oyster shell/southdownsand/cement mix for diy rock. I think I am going to try the solar salt addition to my mix. Maybe stupid question, but, how does the salt left in the rock dissolve when it is encapsulated in the concrete?

 

[GuySmilie]

No such thing as a stupid question!
Put a teaspoon of table salt in a large glass of water and let it sit on the counter. Come back in a few hours and the crystals will be dissolved. In its 'natural' state, cement is not waterproof. It still gets wet to the core when standing in water. The resultant saline solution created when the salt crystals dissolve are leached from the cement by osmosis.
Guy

 

[ebe]

<a href=showthread.php?s=&postid=9349049#post9349049 target=_blank>Originally posted</a> by GuySmilie
No such thing as a stupid question!
Put a teaspoon of table salt in a large glass of water and let it sit on the counter. Come back in a few hours and the crystals will be dissolved. In its 'natural' state, cement is not waterproof. It still gets wet to the core when standing in water. The resultant saline solution created when the salt crystals dissolve are leached from the cement by osmosis.
Guy

Thanks for the reply. Do you know how long it takes to leech the salt completely from the interior of the rocks?

Thanks, Norm

 

[GuySmilie]

Nope! Haven't made any yet. Still too cold outside
But osmosis is most active when there is a substantial difference in salinity between the opposing compounds. So based on that theory, it would leach out of the cement quicker if the cement was soaked in a non-saline solution, like fresh (or raw) water.
Guy

 

[speckled trout]

Just to clarify, the diffusion of water is called osmosis. The movement of salt, from a high concentration to a low concentration is called diffusion.

So, water will soak through solid layers of cement? Didn't they use to produce ships from cement?

Are you sure the salt actually diffuses from within the cement? That would mean the molecules of salt are smaller than whatever "microscopic pores" might be present in cement, wouldn't it?

 

[GuySmilie]

OK ya got me red handed.
I'm not actually a scientist.
I'm a bank robber :uzi:
......but I did stay at a Holiday Inn last nite!!