In some severe instances "all-volatile treatment" (AVT) programs, for instance using only nitrogen-hydrogen compounds such as ammonia and DEHA, have been adopted to avoid the control problems caused by phosphate hideout. 

AVT programs, however, are not universally appropriate, especially in drum-type boilers.

In an All Volatile Treatment program the boiler water is unbuffered and thus it is subject to extensive and rapid pH excursions in the event of feed water contamination, and therefore such a program has no tolerance for condenser coolant inleakage unless condensate polishing is provided. 

An AVT program Is therefore a realistic alternative only when feedwater and condensate quality meet the rigorous standards required for AVT. 

In the 1000-1800 psi (70,307-126,553 grams/sq. cm) range (large industrial boilers and small utility boilers), a AVT program that incorporates the maintenance of very low levels of free hydroxide alkalinity have at times been preferred over the more stringent Congruent Control approach.