Don't know. That blade hangs way out there, and weighs about 200 pounds. The weight box I'm looking at weighs 132 pounds empty. If I use rocks for ballast, I suppose I could get it up to 350-400 pounds. The box has a sliding front plate for loading ballast. Any suggestions for easily removable and heavy ballast would be welcome.
If you want the most weight cast iron or steel. If you can find some cast you know is scrap it can go in with rocks or concrete. The two I built we just filled with concrete but we built them reasonably large compared to the boughten ones I see. The one boughten one I have I just filled it with crushed rocks with fines then put a 4" concrete cap to make the top flat and solid. If for some reason you want to load/unload it things become more complicated. If I wanted removable weights I would probably go to a tractor salvage and build me a 3pt rack to hold whatever front tractor weights were the cheapest I could buy. Salvage yards have piles of oddball weights along with the ones they can actually sell.
I don't hardly ever use the weight boxes any more because most of my work is now out in the open. A box blade sits on the back anytime no other implement is used and they sit pretty compact on the back. Welded a receiver hitch on the back of it so I can move non-heavy trailers without unhooking the box blade.
As far as fluid, we have went exclusively to windshield washer fluid. I think we pay 50 cents a gallon in 55's from our oil distributer. Back in the old days when our row crop tractors with skinny tires needed all the help they could get, we used a calcium chloride solution for significant added weight (much heavier than plain water). But invariably at some point in the tractors life a leak or seep would occour and there goes your rim. Very corrosive stuff and now fewer and fewer tire dealers want to mess with the stuff. This last spring we had to replace all 4 rims on a Cat IT28 articulated loader because the previous owner had filled all 4 tires with calcium chloride and all 4 of the split rims were no longer safe to use because of rust. You have to keep the fill at 75% or more to keep the insides of rims from rusting also. With todays large tractors and fat tires and duals we just figure the ballast needed and have our tire dealer pump that amount of washer fluid in each inner tire. Or in the case of loader tractors, just the rear singles. We do not have fluid in all tractors, just the ones that had inadequate cast weighting. If a person is far enough south where the tires will not freeze, ordinary water will work.
Fluid in tires does complicate fixing flat tires so it is not an entirely best way to go. But it is one option, and it does keep the center of gravity low for loader tractors. Cast iron weights are not cheap any more.
If you want to see some cast iron weights on tractors these are the two latest tractors I have purchased. Front, side, top and rear depending on the tractor.
Versy 500 rack of cast iron weights behind cab and another above rear axle
JD 9630T rack of weights front and full rack on each side. No front idler weights though.
