"algae bloom" i am guessing you are talking about the planktonic algae that forms pea green water when at a heavy population. Planktonic algae is very easy to control with UV, but the water flow can not be too fast for the particular light strength of the UV; otherwise, UV will not be effective.
I would call any noticeable algae outbreak as an algae bloom.
There is a brown algae that is pretty easy to clean up. I just disturb the water a bit in the general area of the brown algae and this stuff flakes off and goes into my skimmer.
Other types of algae take a bit more work like Sissy described. Take the time to apply a chemical and/or elbow grease and the algae gets knocked back temporarily.
I would never continuously use a UV system. Planktonic algae can be useful at a healthy level since it can help compete with other types of algae. Often, I have read about pond folk experiencing a different type of algae when they finally knock back another type of algae.
You are going to have algae, period. All you can do is ask "how can you work with algae by having the algae help you instead of being an eye sore".
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Personally ... What I have done to knock back algae, seems to work so far and we'll see by Spring of next year, is ...
1) very slow trickle water change that results into a 30% weekly water change and keeping my pH in the 7.5~7.7 range. Only trick with a big water change, either slow or not, is the potential pH swing. If you do 30% all at once, then you are likely going to notice a pH swing at some degree. Also, if ya get city water that has noticeable chlorine or chloramines, then you will need to add a water treament if ya do a big water change at once. If it is practical to ya, then I would pre-treat the water pH in a 55 gallon barrel or a bigger tank (maybe like a big cistern tank used for rain harvesting) prior to adding the water. Big water changes also helps to control other nutrients such as Phosphorus. Phosphorus is only depleted one of 3 ways; plant/algae consumption or changing water or chemical binders. I use the exiting water from the change to water my trees and flower beds, which is probably really good nutritional water for them; so, I am not just dumping the water down a drainage trench.
2) A good bio-filtration will help speed along the nitrification to hopefully keep the Ammonia less available to algae. Algae consumes ammonia directly. If there are Ammonia spikes and other appropriate nutrients available, then I think it is likely you will notice an algae bloom. This is why I think pond folk always experience algae blooms early in the year when their water is coming out of a cold spell. Most of the important bacteria hibernate or die off in cold water temperatures; so, it takes time for them to recuperate. I think this is why open air wet/dry bio-filtration such as fluidized bio-filters and trickle/shower tower bio-filters work so well since the bacteria can adjust very quickly according due to water chemistry's volatility.
3) Keep some algae growing. I am still keeping my stream algae growing, trying not to disturb it, in my streams, and I never us a UV light unless my planktonic algae becomes too heavy.
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So I guess the stream algae, big water changes, good open air wet/dry moving bio-filtration, and lower pH is helping me so far. I will just have to find out how everything works out when my water comes out of a cold spell next year. I am also thinking a phraxionator might help knock back algae by removing some disolved organics, which help create Phosphorus and other nutrients for plants/algae.
I just find it interesting how these blooms come and go. It has to happen for a reason. Water chemistry's volatility and nature's slow to react either bacteria dieing off or nutrients less available or influx of nutrients or combination causing these blooms to come and go,
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Easy to find an answer on how to combat algae by knocking it back, such as which UV setups work to knockback planktonic algae and which chemicals or techniques to knockback other type of algae.
It is easy to find people that will reply how particular methods "do not work on their own".
I think it is a combination of them all that is what helps to knockback algae effectively ... since everybody apparently doesn't get the special algae fighting algae or bacteria ... well, not yet, that is until it can be bought on a store shelf.