Well, first, you have some stocking issues. The plecs can get 12-18", the tinfoil barb 15". These fish will need a tank upwards of 75 gallons for long term housing. The red tail shark, while only 6", will likely get aggressive as it matures, and may become a terror in a small tank. It and the tiger barbs will pose problems for the gouramis' long trailing fins. At the very least, the plecs and tinfoil barbs have to go, and you may have to make a choice between the semi-aggressive tigers and shark and the more peaceful and vulnerable gouramis.
As for the immediate problem, your ammonia is also very high - anything above 0 is potentially bad, and anything above 0.25 is cause for immediate concern. The only way to control ammonia and nitrite in your situation are regular water changes, likely 20-50% daily until the cycle is complete.
Rehoming the plecs and tinfoil barb will reduce the bioload on the tank, speed the process, and reduce the ammonia and nitrite buildup between water changes in the meantime. The only way to speed the process is to introduce filter media from a mature tank into your filter. There are many products on the market that supposedly do this for you, but the majority don't work, and the rest are unreliable at best.
Red algae isn't harmful unless you have a planted tank (in which case it's a sign of low CO2), however, it can get unsightly and with the exception of the true siamese algae eater (which is hard to find and easily confused with the flying fox and a couple other similar species, and can't be mixed with your red tailed shark), no algae eater will really go for it.
