Ah yes! I've found many interesting articles on that page Definitely worth a look!

You are welcome. I found this article helpful as well.

That's a great article Thanks Max.

Max, THANKS FOR SHARING, very good articles. KARMA 

It'll help a lot, I am positive

Wow I never knew somany things caused algea!

Kara is fine and helping me to deal with the nasty bba developed on my java ferns. I started Flourish excel a couple of days ago and she is now more than ever interested in it. Probably because the bba started to fade away it became as I assume more tasty to Kara so she is really feeding on the algae. :-)

Good article, answered my questions on brown algae!

hi poppy

where is your tank located is it in direct sunlight as that will cause algae. how often do you feed and how much. hope you get your problem sorted out. 

How big are the fish? because at full length 2 fish will need 80 liters.

Great article, it answered a few of my questions as well about brown algae...been having quite an outbreak of it in one corner of my tank and just can't get it under control.   thanks again, Max!

Poppy: How big is the tank, and what kind of filtration do you have?
The size of the fish doesn't matter, they still produce a whole lot of waste so they need the extra water. 80 liters is an absolute minimum for two goldfish. I'd rather go for a 100L.

Keep testing the water daily for a few weeks please, if you emptied the tank 100%. It will need to cycle, and during this time, your fish will be exposed to ammonia, which is highly toxic to fish!
If you can't bring a sample of the water to the pet shop many times a week, just change it every other day, just to be safe Take out at most 50% 2-3 times a week.

He's full of cr*p as usual, most pet shop workers are :/
Plants don't need to be exchanged, at most because the goldfish are eating some of them But if you'd go with Java Fern or -moss and various types of Anubias, they should leave them alone
The plants will not encourage algae, but actually kill them, since the plants use up the nutrients in the water that the algae feed on! However, goldfish do like eating green algae, and having a few patches of those on the back glass are just natural and fine

If you're not sure how big a tank goldfish need, I'll give you a small chart:
1 goldfish - 20 gallons/80 liters
2 goldfish - 20-30 gallons/80-120 liters
3 goldfish - 30-40 gallons/120-160 liters
4 goldfish - 40-50 gallons/160-200 liters
5 goldfish - 50-60 gallons/200-240 liters
etc.

You probably noticed that one goldfish needs 10-20 gallons to be healthy, if you have common, comets, shubunkins or other cigar-shaped goldfish, go for the 20 gallons per fish (or 80 liters). They are fast swimmers and need a lot of space to be comfortable
Fancies will be fine as long as the tank is bigger than 20 gallons but you calculate it for 10 gallons per fish. (or 40 liters)

Not to mention that no matter how big a tank you buy, your filter needs to pump at least 10 times the amount of water the tank holds, as in, you have a 40 gallon/160 liter you need a filter that pumps 400gph/1600 l/h as a minimum. In my 317 liter tank, I've got two filters, each pumping 1500l/h each, so all in all, they pump 3000 liters, just about 10 times more

Remember to always change the water regularly as well, 50% weekly is ideal for an average size tank (a few hundred liters), make sure you won't overstock!