Technical
- Cloudy, still days - Hot, humid days - When the water’s nutrient content is high - After a chemical application
Nature has provided a clean-up process that will metabolise or decompose excess nutrients. This is called organic digestion and involves two types of naturally occurring bacteria present in all lakes and ponds. Known as aerobic and anaerobic bacteria, the most effective is aerobic bacteria, which only lives in the presence of oxygen. Highly efficient, they are roughly seven times faster in organic digestion than anaerobic bacteria. Anaerobic bacteria, on the other hand, exists in oxygen deficient water and soil and are much slower in breaking down nutrients, allowing soluble organic nutrients to recycle into the water column. Noxious by- products such as methane, ammonia and hydrogen sulfide are created by anaerobic decomposition. Balance is critical to the aquatic ecosystem; without it, water will suffer. There are many steps that can prevent an imbalance from occurring and knowing the causes will assist in determining the best solution for application. Some methods include proper pond construction, chemical applications and the addition of oxygen through aeration systems and devices. Natural aeration is the ultimate method but, when that fails, the next best thing is professional aeration. Creating currents that eliminate stagnant water, aeration mixes the cool water at the bottom of the lake, reservoir or pond with the warm water at the surface, thereby helping to eliminate thermal stratification. It also replenishes the depleted oxygen, encouraging the production and longevity of healthy aerobic bacteria that consume excess nutrients and returns the water to a healthy and stable ecosystem. Professional aeration systems provide many benefits, but most importantly they improve water quality leaving clean, healthy ponds and lakes.
There are three types of aeration systems available:
Surface spray systems: these systems provide the best aeration and vertical circulation in lakes less than fifteen feet deep. Mixing surface and bottom waters, they break-up the thermal stratification, whilst creating convection patterns that break-up mats and clumps of algae and discourage mosquitoes from breeding.
Horizontal aspirators: ideal for lakes ranging from three to twelve feet in depth that will
benefit from a strong directional flow. These aspirators create artificial currents in irregular shaped ponds and lakes, breaking up algae mats in stagnant waters. They are chosen when no spray pattern is desired.
Air diffusion systems: onshore air compressors pump air to diffuser manifolds at the bottom of the pond or lake. Most effective in waters with depths greater than fifteen feet, they can also work in waters as shallow as four feet. In general, any bottom diffuser loses roughly fifty percent of its aeration and mixing capacity for every three foot increment of depth shallower than fifteen feet.
On a commercial level, the difference a water feature can make is invaluable. Recently, two customers - one a golf club and the other a commercial company - had the issue of stagnating water, which was starting to smell. Brickendon Grange Golf Club in Hertfordshire opted for surface spray aerators for its two problem ponds flanking the eighth and eighteenth holes. The Fractional five-in-one system chosen has brought clean, clear water to the ponds and, at the same time, created two new beauty spots for golfers to enjoy. The Fractional aerating system can be relied
upon to keep the ecosystem of any smaller area of water in perfect balance thanks to its ability to transfer an impressive 1kg/2.2lbs of oxygen per hp/hr and its pumping rate of 115m3/ph. Similarly, when the lake at the Ballycoolin
branch of digital printing company Xerox in Dublin was at risk of becoming stagnant, a Gemini aerating fountain was brought in and has transformed the landscape. The 3hp surface spray aerator was favoured
for its dual ability to circulate the water and provide a striking feature for office workers on the business park to enjoy. As functional as it is beautiful, the power of the system allows it to move over three times more water than decorative pattern fountains, delivering customers visibly healthy water as well as an appealing aesthetic. Water quality management is a science and
every lake, pond and reservoir is different. Hopefully, this article will help you identify problems earlier, consider prevention rather than cure and provide some solutions to existing issues in order to create water features for everyone to enjoy for years to come.
Otterbine products are distributed in the UK by Reesink Turfcare. Email
info@reesinkturfcare.co.uk,
www.reesinkturfcare.co.uk
PROBLEM CHECKLIST: WHAT TO WATCH OUT FOR 1 Toxicity of water
Public health risk from foul water containing faecal coliform and blue/algae. Once reported, lake can be quickly closed to the public
2 Smells/stench
Caused by anaerobic bacteria which, because they contain no dissolved oxygen, produce methane and hydrogen sulphide
3 Decline in attractiveness and visitors
People like water features, when they stay away from yours, it means you have a problem
4 Decrease in wildlife
A healthy, well-maintained lake will attract wildfowl and add to the beauty of the scene
5 Dead fish
Ugly and offputting to visitors. A well- managed lake can expect increasing fish populations and associated wildlife, with very few dead fish
6 Chemical treatments
Reversing the decline and clearing up is costly. Prevention costs much less and frees your budget for other things
7 Bugs and mosquito larvae
People don’t like bugs! Insect infestation is dramatically reduced when a lake is well balanced and properly aerated
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