diet
Fish Crazy
Do you know what sort of algae you have? Not all algae is caused by too much light, some algae is caused by too much or even too little nutrients in the tank, while other types of algae can be caused by things like too little light. How long do you leave the tank lights on per day and what are your nitrate readings and does the tank have any healthy live plants? How often do you do water changes and how much water do you take out/replace on average?
Your tank is overstocked, so you should avoid adding any more fish if you can (even though oto's make good small and efficient algae eaters, they are very sensitive to water quality and don't cope with stressful conditions/situations very well, so don't make good fish for crowded tanks).
the lights are on for 12 hours a day, as reccomend somewhere here on this forum.
Nitrate is 0the tank has several java ferns that are as healthy as can be.
water change info is above.
Ive decided against the otto's allready because of numbers and the unfriendlness reported in some community tanks.
The tank lights really don't need to be on that long especially if the tank is getting a lot of natural sunlight. Java fern is a generally very undemanding and hardy plant to look after, it can do fine with very little light, i would advise leaving the tank lights on for a lot less (like only having them on when you are around the house and want to see the fish in the tank).
Increasing the amount of plants you have in the tank can also help fight and eradicate the algae, as algae is not a very advanced/evolved plant and usually only thrives when the existing plants already have more nutrients and light than they need, or are dying due to various reasons and giving the algae a chance to take over. It doesn't do well with lots of competicion from more evolved aquarium plants, so if you stock up on more healthy live plants, they will start to out-compete the algae for resources and it will die off .
in 4 weeks time i'm adding more plants, when i have a wood piece to add and i will leave on the light at night!