saw a piece no heavier than about 1k - 1.5kg at the weekend.....£7.99!!!!!!
to keep cichlids you are really gonna need a tank of no smaller than 40+ gallons. That means a hefty amount of rock to make it decent!!
to be honest have heard good and bad reviews about tuffa anyway but never used it myself. Apparently not great for water parameters, which is important when keeping cichlids such as mbuna.
I posted in this section myself just yesterday querying rocks etc. Have a look at it.
I checked out B&Q and they have some great rocks, stones and boulders for a fraction of the price (£9.98 for a 17.5kg bag!!!)
No tuffa rock though so if your heart is set on it you are gonna have to dig deep into those pockets!!
You can use tufa rock for mbuma tank it helps lift the PH.
Iv got it in my tank.
Search on Google, Tufa (not Tuffa) click u.k only and it has links to aquaria sites that sell bags of it. click here
No probs Mate.