general hydro ph down, liquid or powder?

Its time to get more ph down for my resovour. I just went through a quart of the liquid and have to use 1/2 cup to adjust my 25 gal resovour. Im wondering if its more cost effective to buy the powder, 1.5 lbs for about $15 or 4lbs for $28, or buy the liquid gallon for about $35 this time. Anyone used to powder and think you get more out of it then the liquid?

Anyone use the powder ph down or another brand you like? I want to buy it tonight and plannig on buying a large amount. Any help will be appriciated.

I use the General Hydroponics dry PH Down
All ways buy dry. why pay for water.

Thank you. I ordered 4lb of the dry ph down. Hopefully it lasts for a while. =)

i like advanced nutrients pH up and down (it's the only thing I can afford by them anyways). It's SUPER concentrated. Only takes a few drops for my 5 gallon resevoir. Lasts me a lifetime and it's not that expensive when compared to GH's pH up and down.