Algae pond problems ... thick algae questions

Dear Ben, I have an annoying problem with my pond and wonder if you can help. I have a lined pond approx 2,200 gallons. I have a Lotus 12,000 pump going to a TMC 25W UVC, then a Yamitsu 60W UVC, both with clean sleeves and new bulbs. This then goes into a large filter box with sponges and flocor, then returns to the pond on a waterfall. All hose is 1.25in. I have an air pump with two air stones and six large koi.

• I have asked five different koi retailers and they have all come up with different solutions, none of which have helped.
• The problem I have is that there is a thick layer of algae all over the top of the water, although the water underneath the algae is clear and it is possible to see the bottom.
• These will work in conjunction with each other (and your filter) to flocculate and remove suspended algae - producing the crystal clear water that makes it 'possible to see the bottom'.
• In your own case (and the majority of other ponds filtered with a UVc), the most common side effect is the proliferation of other nuisance algae - such as filamentous types (blanket weed).
• One of the starkest and most fundamental differences between the natural and manmade systems is due to the role that plants play in creating and maintaining a balanced pond environment.
• As koi keepers, we try to do our best to resist the growth of nuisance algae as strongly as possible, but the battle is relentless and we are usually happy to concede and settle for an uneasy truce.
• The 3 key factors that stimulate its growth in your own pond will be: Sunlight, Nutrients and Temperature
• These are readily available in tap water or indirectly through fish metabolism.
• Wherever nutrients abound, so will this opportunistic algae, being the first to capitalise on ideal growth conditions.
• Because your koi pond is an unnaturally stocked and relatively over-fed environment - nutrients will abound.
• You can often see the evidence of the mass of fine bubbles that are released during photosynthesis by observing rafts of blanketweed rising to the pond surface in the day (buoyed up by oxygen bubbles that become trapped within the filaments), sinking to the bottom again at night.

pond algae blanket koi water filter growth nutrients sunlight plants filaments balance installing UVc environment click link to read full article