Well as for the plastic- I/ve seen several differnt ways to go about this( the plastic I got is easier cause we have thousands of pounds of it @ work ) anyway the first batch I tried I used cut up straws and that works ok but I went to the regrind for mainly to lighten up the rock some. Also if you go to the GARF website the use basicly scrap plastic from another factory but the say to buy some pvc of other plastic and drill through it and keep the little pieces that come off of the bit. The reason to use plastic is that the coraline grows really good on plastic . But you don't even need it, just get crushed oyster shells ( call a local feed store 50lbs for around $6 ) and get some portland cement type I,II,or III
I used type I bnecause its all I could find, but from what I've heard from other people type I/II is better because its stronger than type I , anyway 95lbs costs about $7 at Home Depot, Lowes ,Menards,etc.. I mix about 4 or 5 parts shells and 4 or 5 parts plastic to 1 1/2 parts cement and then mix it up ( a paint stirring thing that you can get for a power drill work good only a couple of $$$ ) then I let it set for 1/2 hour to an hour and I mold it on a peice of plywood into the shapes I want . I use bollons to make cave and I've used a water bottle to make an over hang. You could also use sand to mold you cement but its a pain to get all of the sand off of the rocks, I find it easiewr to do it the other way. ive also hear of people putting air tubing int the rock for latere use..some one did that so it would be easier to feed some coral and another to use it for air bubbles .
I tried putting pvc pipping inside and then drilling holse in it and then driiling into the rock as to create more water flow throught the rock, but I've gotten the batch down now and the rocks are very pourus and dont need any help.
Well that is alot of info here let me know if any helps or if you need more....
O yea curing well you just put them in water in tubs or a garbage can and change the water twice aweek or more ( what ever you want, I do it every day I figure get rid of the old ph heavy water and start a new) for 3 to 4 weeks and then 1 or 2 weeks in salt water and your good to good. I even put on in my tank that hand't cured and I haven't seen a increase in my PH yet
so any more questions , go ahead and ask.