DIY Aragocrete Rack pH/alk spike question

[tbrown]

Ok, so I decided to make an Aragocrete frag rack using Portland cement and aragonite sand. It's very small - maybe 3/4 cup of cement and 1 cup of aragonite sand plus a tablespoon of rock salt. I used egg crate for the "frame". My question - I have a 125 gallon tank that's been running for about 9 months now. I have probably close to 25 pounds of Aragocrete rocks that I made several months back and freshwater soaked for about 2 months, watching the pH, and then saltwater soaked for another month. When I added these to my tank, I added them about 4-5 pounds at a time and never noticed any pH or alkalinity spike - I didn't really expect any since the soaks took that out for the most part.

My question: how much of a pH or alkalinity shift should I expect if I don't let this thing soak or soak it for a short period? Again, 125 gallon tank plus sump, 3/4 cup of Portland cement max, probably closer to 1/2 cup.

 

[Jason_MrFrags]

With a small amount of diy rock you may not even notice any change.

 

[tbrown]

That's my thought. I have about 30 pounds of rock I made previously in my tank and I never noticed a spike but I did freshwater soak for a month and a half before saltwater soaking. I also only added them once every week or two. I'm thinking I'll let these soak until the water stops clouding and then do a saltwater soak for a week with some cycled media to start the seeding. I'll probably dose some phosphates as well to try to eliminate the phosphate stripping once I add them to the tank. Already having a hard enough time keeping the phosphates elevated to detectable levels.