Perhaps a UV sterilizer is right for your aquarium

I continue to follow the threads on forums, aquarium articles, and blogs about UV Sterilization.
It's a very simple process using ultra violet (UV) light for rendering sterile unwanted free floating bacteria, algae and parasitic organisms, like ich. The UV sterilizer light affects the living cells by altering the structure of the cell's nuclear material. The end result is the organisms fail to reproduce, eradicating your aquarium or pond water of these unwanted nuisances.
Tropic Marine Center Pond Advantage Professional UV Sterilizers for Ponds or aquariums
UV (ultraviolet) Sterilizers are great supplementary devices for both freshwater and saltwater aquariums. Used in conjunction with your primary filtration system, UV sterilizers offer unique benefits from water clarification to effective management of various waterborne microorganisms including free-floating algae. Algae, parasites, and bacterial diseases are a nuisance in any aquarium. There is nothing more disheartening than watching hours of constant aquarium maintenance come undone. If green water, algae blooms or persistent diseases plague your aquarium, consider combating the problem with a UV sterilizer. • UV Sterilizers and bulbs are safe for freshwater, ponds, and saltwater aquariums;A MUST READ article for anyone looking to get the most out of their Aquarium or Pond UV Sterilizer!UV Sterilizers are recommended for all saltwater and freshwater aquariums and for ponds.
When using a UV Sterilizer in a home aquarium, the UV unit should be placed last in the filtration line. You want to first filter the aquarium water through your and then run the water through the UV device before returning the water to your fish tank. By first removing the solids in the aquarium water with your mechanical filter (canister filter, etc), you are helping your UV unit to attain maximum operational efficiency.
First the Proprietary Heavy duty 13 watt and 9 watt UV Pump/Filter design with double O Rings seems to have solved the leakage/UVC short problem for the most part, and the flow pattern/design is also improved over earlier Submariner and similar models.

One negative is "rated" flow rate, however as per our tests this "rated" flow rate is not the actual flow rate; the actual/adjusted flow for certain proprietary units by AAP is much better for level one UV Sterilization.
The propeller design of the impeller has little head pressure which actually is better for maintaining a flow rate of 25 gph per watt in the vertical configuration.
However, the flow rate is not good enough for circulation of very large aquariums or ponds, so for this reason other circulation pumps should be utilized so and I advice to not depend upon these UV Pumps as the primary mode of circulation.The plus side to these submersible UV Pump/Filters is the need for no additional plumbing in aquariums or ponds, not that splicing a line for a TMC or Terminator UV is all that difficult (with ponds though, extra devices such as UVs can sometimes be a bit more of a plumbing project).

However the another entry into the field of Internal UVs are still incorrect as per their flow rate (& construction); The AquaTop UV Sterilizer Pump 3, 5, 7, & 9 watt are actually no better than the Submariner or similar early generation Internal UVs (please read more about these later in the article).Adding an aquarium UV sterilizer to your tank is like insurance for your home or apartment. Proper use is reliant upon proper aquarium care, such as regular water changes and filter maintenance. UV only targets free-floating microorganisms, not nuisances attached to your fish, substrate, plants, decorations, or corals. For optimum performance, UV sterilizers should be placed after your biological or mechanical filtration. Also, the flow rate through the sterilizer should be controlled, based on the manufacturer’s recommendations. This ensures the UV sterilizer is targeting microorganisms – not debris – and has the correct amount of exposure time to eradicate (kill) the nuisance. Your chosen UV sterilizer will have easy-to-follow guidelines for both setup and use. UV sterilizers can be set up in a variety of configurations, be it stand-alone or housed inside a canister filter, hung on your aquarium walls or tucked inside your aquarium stand. They are available in a variety of models, each designed to target aquatic nuisances, not your budget.