Frag rack experiment

[Joekovar]

I had material left over after doing my tank structure so I experimented with doing a sort of natural looking frag rack.

The skeleton is pink high density foam. It was misted with water and coated with alternating layers of Portland cement and aragonite.

I carved cones out in the back and encapsulated neodymium magnets in the cones. It won't hold it's own weight when sticking it to the fridge now that it's coated, but I'm curious to see if the boyancy of the foam and a second pair of magnets outside the tank will support it's and some contents total weight. (It might just float...)

I doubt I'll use this thing any time soon, but it was fun to make nonetheless.

 

[45ZoaGarden]

Looks cool!

 

[Bryce M.]

I like it! I've seen racks that are fake rocks with holes in them but this would be able to hold more

 

[Zos4me]

Very Nice

 

[lilgrounchuck]

Awesome! I’m needing to make one myself and I may steal that idea. Curious as to what your mix ratio was and how long you cured it before adding the scape stuff to your tank? I like the texture it came out with.

 

[Mical]

Genius starts with an idea & that my friend, is genius!

 

[Joekovar]

I tried mixing up Portland cement and aragonite then applying it with a typical air compressor powered texture hopper, but it wouldn't shoot untill I thinned it out way too much, by the time I got anywhere with that hopper the aragonite just started bouncing off and all I got was a mess.

So I moved to using a spray bottle full of water to mist it, then I hand dusted it with dry cement until the cement stopped darkening from soaking up water, then I misted it and hand dusted it with small aragonite gravel, and repeated that for multiple layers.

I kept it moist with the spray bottle over the weekend, then I sprayed it in the morning and afternoon for about a week until it didn't change color when wet.

The structure I made for my tank has spots where dusting collected at the base of columns, resulting in mounds of cement that didn't get properly hydrated while making it. After a couple of weeks submerged in tap water and being dosed with 20-30ml of white vinegar daily I started to get white crystals growing at the base where this malhydrated cement collected.

I think the trick to using cement is to control the thickness and hydration of the cement during construction, being careful not to under hydrate sections as they will eventually hydrate when submerged and cause trapped chemical reactions.

I don't think mixing and molding would work as well as misting and dusting. You get significantly more control with misting and dusting. I did it by hand, literally throwing clouds at it, but I think a flour sifter would work much better.

 

[eggplantparrot]

that's gunna float lol

 

[Joekovar]

that's gunna float lol

I think you're right.

I've since wrote a calculator that tells me how much the total structure has to weigh to create a neutral boyancy for the volume of foam used.

 

[Larry L]

Pretty cool, do you need to do anything to seal or treat the pink high density foam, or is it safe in the water as-is?

 

[Joekovar]

That's a tricky one. I've found mixed answers about the foam, and I've yet to find someone who came back long term on a current build with it saying one way or the other.

I did come across one person who mentions they've used the foam for years in freshwater settings of museums, but they had no experience with marine settings and I'm thinking the product has evolved over the years.

There's half a dozen or so versions of the product on Cornings website. I'm using the general purpose xps version. (Moisture resistant, not moisture impervious one)

I've got about 3 sqft of 1" thick in a 55 gallon tank now. Been in there for a few weeks with tap water. I added salt and brought salinity up to 1.024 Friday evening. Going to add a bottle of Dr Tim's one and only tonight and start dosing ammonia.

Once it's cycled I'll add a few Humbug Damsels and keep a close eye on them. I figure everything's been submerged long enough for leeching to happen if it will. I already went through carbonate formation on the cement so I think the worst is over there.