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Should I use salt in my Watergarden?

I have and still am using several different kinds of water filters some commercial and some homemade. By for the best way to clean water is to run all or part of the water through a gravel bog containing a good number of aquatic plants. (more info on filters) The Illinois River is the best example - gravel - plants - and running water equals clean water. Pollution of all kinds are removed from the river within 1 mile or less.

Another product I use is plain old noniodized salt. Salt starts killing algae at 2 pounds per 100 gallon of water. That is 2 tablespoons per 5 gallons.

The thing to remember is that salt can build up to a toxic level with repeated applications.  Salt is removed only with water change, not by evaporation.

A simple test for salt is to touch your finger to your pond water and then to your tongue. The taste buds cannot detect less than 7 parts per 1000. If you can taste salt there is enough to kill algae.

Fresh water fish need some salt. Salt contains potassium which is a necessary part of fertilizer for the plants. Potassium is not natural in fresh water. Parasites that get on fish go through 3 phases or life cycles. First is the egg, next is a free swimming larvae, and third is the adult that gets on the fish. Salt kills the free swimming larvae.

Salt is a tonic for weak or stressed fish. And is recommended when transporting fish. Salt can be used to disinfect new fish and plants before putting them in your pond. A 10-15 second dip in a 5 gallons of water with 1 pound of salt will kill parasites and algae on fish and plants.

2 - 2 1/2 pounds of salt per 100 gallons detoxifies nitrates (fertilizer). Even Clear water can contain dissolved fertilizers or nitrates. This comes from fish waste and decayed organic matter in the pond. 

When the weather hits 80 º F the water can turn green overnight. A good biofilter will slowly put things right. Salt kills the algae and neutralizes nitrates that feed the algae. This speeds up the bio-filtering process and does not harm the bacteria in the pond.

For string or blanket algae broadcast dry salt directly onto the algae.

Another problem we have is good old black muck on the bottom of the pond. That does not get pumped into the biofilter. One thing I do is put a small catfish in each one of my ponds. They don't compete (or eat) goldfish or Koi. Catfish are night feeders and they plough thru the muck looking for food like bloodworms (1/2 inch aquatic red worms). The pump picks up the stirred up muck and the biofilter catches it.

Another good product is a dry enzyme that works in winter and summer. It is also sold as Rid-X for the septic tank. It eats dead organic matter and does no harm to fish or plants. It should be applied at a rate of 2 oz one time per month. If there is a lot of muck the water will be tinted brown when the black muck is dissolved back into the water it will clear up on its own in a week or so.

For worse than normal problems with dirty water or algae a good solution is to replace the water. Pump out 1/4 - 1/3 of the water and refill the pond one time per week for 3 - 4 weeks. When you pump out 25% of the bad water you get rid of 25% of the problem. It is safe to refill with chlorinated water at this rate.

Feel free to e-mail further questions. Remember advice is always free!

Glenn