Floating voltage should not go higher than 13.80V and only 5% of the maximum current to maintain the 13.80V. You should really only go to 14.2V if you cycle it regular.

When charging a SLA you need to limit the current otherwise if you get the battery to hot the gel will crystallise the gel inside and the battery will not hold the charge. There are quite a few designs out there, I used to build the SLA chargers for the golf buggies the golf trolleys and sell them has a product I only used the L200 2 Amp regulator with a few components, 2 Pots 1 for setting the maximum voltage (open circuit 14.4V) and the other to limit the current along with a couple of LEDS to let the user know the when it was bulk/float charging. Once it was set to carry out a full test and leave it charging sometimes a little adjustment was made to maintain the 13.8V.

I will try and see if I can find it (if I still have it) and upload it,