Philanthropist said:
Recently I've noticed a darkening of my pond's water from clear to light green, green, now really dark green. I've treated the water with tetra pond algae control, but it has yet to show any real results, I've done this for a week by the way. This through is not the first time my pond has had a major algae bloom and last time the algae control worked. I'm considering draining my 300 gallon pond, but I feel that is a bit evasive. Any suggestions on how to clear my pond? I heard that salt is a good algae controller can anyone confirm this. Thanks.
-Philly
Just realized Koi Guy answered this already. Must have started my reply right after he sent his. - I'll put in my 2 cents anyway, but Koiguy definately has more experience with ponds.
What the heck I'll take a stab at it. I must first warn you I don't even have a pond yet. I do however have experience with heavily planted tropical fish tanks. While I know and have been warned not to treat the pond like an aquarium, at the end of the day causes for algae in fish tanks and ponds are the same. So here goes-
To keep green water algae to a minimum you have to fight it like a fire. To fight a fire you need to remove one of the 3 key elements that makes one start or burn. Those elements are similar to algaes 3 key elements. 1) Oxygen = Oxygen of course these 2 are the same. 2) Ignition = Daylight or sunlight. 3) Fuel = excess nutrients in your ponds water.
Well for #1 you need O2 for the fish and bacteria to live so you can't remove that. #2 You can try to shade your pond with trees or some type of screening. You could even cover your pond completely for an extended period of time with a tarp. This is called a "black out". It is somewhat effective but who wants to cover up their pond? I hate this method. So last but not least #3 Fuel - exscess nutrients. Well I've learned that this ain't as easy as it sounds. But you have to do the best you can. You need to do your weekly or every few days of water changes. Does this always work? Hell no I say. But if you are not doing routine Partial Water Changes (PWC) then this is step one. Dilute the nutrients with fresh water. Less nutrients = less algae. Here's the catch - What if your water supply is part of the problem? Sometimes you are actually adding nutrients to the water. Private well water and municipal supplied water may have up to the "legal limit" of nutrients already in the water. There can be Phosphate, Nitrates, and Ammonia (a form of nitrogen algae uses as food) not to mention other "good stuff". Fish also need Phosphorus in their diets. I can't think of one commercial fish food that doesn't have it. So excess rotting fish food, fish waste and possible added nutrients from your water source + daylight + oxygen = pond water that looks like Mountain Dew.
Phil - Assuming you are right on top of PWC's and routine maintenance weekly, you have a few options, one you have already tried. the algecide. Everyone hates resorting to it because we all know it has other ill effects. I refuse to use these products myself. Let's put that off the table.
1) Removing the green from the water with a polish filter. This can be done inexpesively, especially if you have an extra pump laying around or you can plumb it directly into your existing plumbing with a by-pass. It is just an ordinary "Whole House" sediment water filter you can get at Home Depot. A 5-20 micron sediment filter cartridge is perfect. You run your pond water through this and it will be crystal clear. The filter is not intended to be run continuously as it will eventually clog. Use it as needed.
2) UV "filtration" - It works from what I've heard and is probably one of the best options for a pond because of a ponds size. I have never used it but I know it is a reliable alternative.
3) RO/DI filter - Reverse Osmosis Deionized water. For smaller ponds like yours, 300G, you can get an RO/DI filter. The down side(s) are initial cost, installation, storing the water until ready for use. for you it would take about 1 day to produce enough water for a 25% PWC. The upsides - you can also plumb the filter to a sink in the house. The water is good to drink because it is almost pure, no more buying Spring Water unless you just drink your tap water of course. . You will have 7.0 pH replacement water with no harmful contaminates. You control what elements are in your water. There is an additive you can buy for treating RO/DI water for fish keepers. You add the proper elemnets at optimum levels. Other then rainfall or run off you will eventually have "perfect" pond water.
