If homopolymer repeats of the same nucleotide (. TTTTT) are present on the template strand (strand to be sequenced) then multiple introduced nucleotides are incorporated and more hydrogen ions are released in a single cycle. This results in a greater pH change and a proportionally greater electronic signal.  This is a limitation of the system in that it is difficult to enumerate long repeats. This limitation is shared by other techniques that detect single nucleotide additions such as pyrosequencing .  Signals generated from a high repeat number are difficult to differentiate from repeats of a similar but different number; . , homorepeats of length 7 are difficult to differentiate from those of length 8.