Water Changes (Python/Siphon)
by Dr. Adrian Lawler
Extracted from the staff Operational Handbook which Dr. Lawler wrote as Aquarium
Supervisor for the J.L. Scott Marine Education Center and Aquarium, of Biloxi, MS
Aquarticles
In our aquarium, where all the tanks are separate closed systems, periodic
water changes are necessary for a variety of reasons, as follows:
1. Ammonia build-up
- Air was off too long
- Food decaying in tank
- Dead organism in tank
- Too much city water used
- Filter killed by disease treatment
2. Cloudy water
3. pH too high or too low
4. Dissolved organics
5. Toxins (released by algae, or otherwise)
6. Dinoflagellate (or other protozoa) bloom
7. Nitrate too high (excessive algae growth)
8. To add trace elements used up in tank water
9. To unclog undergravel filter of dirt or other debris
For 210-gallon tanks and smaller, water changes are also done with a python (siphon) so
that filter debris is discarded along with the water. A normal water change would be
10-20%. A water change of 50% or greater can result in 210's busting their seams or animal
stress caused by changing the tank water chemistry too quickly.
Water changes should be periodically done through the bottom drain valves of 210-gallon
tanks in order to flush debris from under the filter plate. A design flaw in 210-gallon
tanks where drains are not at lowest parts of tanks prevents thorough flushing of debris.
When a bottom valve (of 210-gallon tank) is opened run a flexible tygon tubing through the
drain valve and under the filter plate with vigorous back and forth movement to stir up
debris so it can be discharged through the drain valve.
There are several ways water changes can be accomplished for our tanks:
1. Siphon water and debris into a bucket (for small tanks and no floor drain) or
onto floor (for tanks having access to floor drains).
2. Python water and debris into a bucket or onto floor.
3. Run rapid sand filters on "Backwash".
4. Run DE filters with exit hose near a floor drain.
5. Open bottom valves of 210's and larger tanks. This should be done at least once every
two to three months in order to discharge debris under the filter plate.
6. Open bottom valves of DE (Diatomaceous Earth) filters. This also discharges the DE
powder and should be used only as a means of water change when the DE filter is going to
be recharged anyway.
Frequency of water changes
- Dependent on biological "load" on a tank (inches of
fish/gallon of water, feeding rate, aeration, supplemental filtration, lighting, and other
factors).
- With an undergravel filter and no supplemental filter the maximum "rule of
thumb" load is one inch of fish/gallon of tank water. The greater the
"load" the more frequent the water changes should be.
- A tank with a heavy load should have about a 10% water change every week. A tank with a
light load can go for a longer time between water changes - sometimes up to several months
or longer. Experience with the tanks can indicate the frequency of water changes.
- No two tanks in the aquarium are identical so all the tanks are maintained differently,
depending on biological load, and many other factors. There is no "Concrete"
rule on water changes which will apply to all tanks.
Frequency of Siphons/Pythons is determined by:
- Biological load in tank.
- Amount of feeding.
- Decay, falling apart of logs and other organic decorations.
- Die off of algae or plants in tanks.
Generally 1/3 - 1/2 of tank substrate (coral, gravel) of 10 to 210 gallon tanks should
be siphoned or pythoned per month. The whole tank cannot be pythoned at once, or within a
one to five day period because too many bacteria get discarded, which can lead to an
ammonia build-up and possible "crash" of tank.
Medium and large tanks are periodically stirred by animals in tanks, by long-handled
net or squeegee, or by putting exit hose of DE filter under water so debris is put into
water column to be pulled out by DE, rapid sand, canister, or bucket filter.
|