Please lay off the Royal Plecs...
Panaque nigrolineatus and its' allies aren't algae -eaters (although they eat algae too) but plant- and woodeaters!! And they like gentle tankmates (wich doesn't include most Rift cichlids), a medium low pH (5,5-7) and soft water. finally; Panaque nigrolineatus gets big...REALLY HUGE. like 2 feet and up....
for obvious reasons, bogwood is not a good idea in a Rifttank. Loweing the pH being one of them.
I second Barbie's suggestion: Ancistrus spp, esp captive-bred ones. Lay off fancy wildcaughts, those are not used to either African cichlids, nor those waterparameters.
Most fishkeepers use a Common Bristlenose (Ancistrus) to clean out any tank, esp Rift. Ancistrus reaches 4-5"wich makes them handy. A common Pleco reaches 1,5 foot, so....
I kinda like the suggestion of using Barbs, for one; it's more natural, sort of.
Unfortunately barbs are rarely imported from the Riftlakes, although there are many from there.
the Chinese Algae Eater (CAE or Gyrinocheilus aymonieri) is an agressive fish, that's a good algae-eater when juvenile, but an agressive slob when adult. They often change their diet when adult to being a lepidophage.....a scale- and skin-eater. Not very nice on tankmates
Other much better Barbs include Garra, wich are very tough. Garra's can cope with Riftwater, and are fairly territorial, but do not eat scales, but algae, also when adult.
Crossocheilus is another great algae-eater. C siamensis, the TRUE SAE, is actually the best algae-eater in the hobby, next to Ancistrus.
It has a few drawbacks: it's a peaceful fish, that reaches 6" and should not be kept single. And it takes some time getting used to pH8. Once eshtablished, it can and will eat algae till it's death.....
and it's very pretty to look at, lively too. 2-4 makes up a nice group. But don't put it in with extremely nasty fish, unless you have a roomy tank. It'll need ome space to avoid hassle.
Crossocheilus siamensis