does anyone know of any harm or cure time for concrete before going into saltwater? i am wanting to do a pillar with suspended "arms" in my 65gal... i saw a picture of it done in someone's tank on here, and was just wondering if concrete was acceptable or how else to accomplish the same thing.
concrete pillars
- Thread starter gaguy68
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Lots of people use concrete to make forms. I use to do it in my freshwater tanks. Made a background wall. The cure time was about 3 weeks....though it could have been faster. I cured it with water in the tank and regular table salt....kept an eye on it till the pH dropped to acceptable levels. Curing concrete has a pH of 11-14. Somethings people use so there isn't sooo much concrete is foam or that builders spray foam to make the form and then put concrete over it...just make sure no foam is showing. There are other ways to make a concrete type using other products. Garfs website has some instructions to it.
It takes usually 2 months for concrete to cure enough to put in your reef tank. I use freshwater to cure the concrete, doing several water changes. Then when the Ph is low enough I put it in a bucket with saltwater. For some reason once it hits the saltwater Ph spikes again. Leave in saltwater about a week, testing Ph. It should then be safe to put in your tank. Do not rush it, I have heard people using vinegar to drop Ph. I promise you that it only drops Ph temporarily. Once out of the vinegar Ph will spike again.
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I made almost all my rock and the ph dropped to an acceptable range in a couple of months but the phosphate levels were pretty high so I waited another month. I also placed the rock outside in the rain every chance I got which seemed to drop the levels really quick. I suppose the reason was the rain rinsed instead of soaked the rocks taking away the bad stuff.
Here is a link to a cultured rock project that failed miserably. The main point I wanted to make is how concrete can hold high Ph levels. Today I got around to busting up this project into smaller rock. Has been sitting in my garage for a year. I put some rubble in a small container of water. An hour later took a API Ph test to it. The reading was off the chart.
