River System - intial study

17 Sep 08

Traditional system

Ever since I started to pick up the hobby to rear fish, one of the action most often I did was to visit the aquarium shop. My visits are not so much interested in the fishes but more on the water circulation system, filtration system and aeration system.

As most other amateur, the first set of equipment I picked up is a 3 1/2 feet length fiber filter tank and a 5 ft diameter poly tank. This filter is then place on top of the tank with some support and a water pump to pump up water into the filter. Other equipment I used is an airpump.

Disadvantages of the traditional system

Not for long I quickly found out that the traditional system has some disadvantages:

1. Fish waste and unfinished food quickly sunk to the bottom of the tank and then after no way out for them! Soon after they will become muddy sediment waste and ammonia starts building up.

2. The sediments will eventually stuff up the inlet of the water pump and the water pump will have to work harder to finish his job well. This will happen within 1 to 2 weeks after the water change exercise and cleaning of the pump. After the pump is stuck, basically very little water can be pumped up until you clean it.

3. Ammonia, the fish' enemy, will develop quickly if water condition is not taken care of. Then after, if the tank is expose to sunlight, algae can grow very quickly too and therefore further reduce the oxygen condition in the tank.

4. Ammonia turned nitrat will slowly got stuck between different layers of filter in the filtration system. Hence, blocking the water flow through the filtration medium, either it is a sponge, biorings or others. The blocked filter medium will attract mosquitoes to breed eventually.

5. Due to the present of sediment (mainly due to fish waste and decay food, water condition in the water tank can never be restored back to the initial water condition. Even though 50% or up to 70% of the tank water will be changed in the system, still the tank can become dirty very quickly if the water filter system is not good.

'Professional fish pond builder' did the same system

After I move to USJ 1, where I have the luxury to have a bit more land, I engaged a so call popular fish pond builder to help me construct a fish pond in the ground. Though the fish pond is big (18' L x 4' w x 4' water level), he did the same system and suggested that the new pond's water need not be changed so regularly. He suggested that his system will work well.

Haven't been exposed to the larger system built by popular fish pond builder, I have given it a try with their idea. He basically adopted similar principle approach. The only different is he has built another pond for filtration purpose. A sketch is as shown below:

He is right in a way where I don't have to clean the pond for the first 6 months. On this point, a note has to be made that during the first 6 months, the pond population is around 50 tails of fish each around 1 kg to 1.5 kg. Second point need to note is that we regularly use the pond water to water our plants, vegetables and flowers.

After 6 months, I decided to take a look at the filter pond. Wa lah! It is filled with a lot of mud and sediments. At this time, the pond's population is about 280 tails of fish. Most of them weigh around 300 to 400 grams.

And it is a tough and dirty job to try clean up the sediments and mud.

A better system is required

Ever since then I kept thinking, isn't there a better system? Can't we have a system which will work closer to the living environment like in the river of Taman Negara? Where the water flow is clear all the time, fish waste doesn't clog up at the bottom of the river, plenty of oxygen and food?

The river system

I begin to figure out this new idea and on 17 Sep 08, it is a public holiday and I have worked out a system as shown below:

The idea is actually very simple. I bought a 4' diameter poly-tank and make a hole at the bottom.

This hole is then connected to the lower filter system via the piping shown.

Water is then allowed to flow out from the tank and flow into the filter system at the lower portion. A simple fish net with fine hole is placed just right after the water outlet pipe to capture immediately all fish waste, decay food and other solid material.

With this, the net is washed twice a day but it is very simple and easy job to do. This will capture most of the solid waste and the advantage is the filter will not be dirty fast.

After the water go through the filter, it will falls into the 4' fiber tank at the bottom. At this place, the rest of the sediment will settle at the bottom and I have a pump to pump up the water to the poly tank again.

By doing this, it is noticed that the pump runs smoothly all the time and does not get clogged up by sediments.

Water pumps up to the poly tank is like a shooter, it makes the water inside the tank circulate. The effect of this circulating water is not known clearly yet but it is noticed the fishes inside will have more exercises to do! An overflow pipe is put in to control the maximum water level.

Below is a short video clip of the swirling water condition inside the poly tank:

Note: the tank is quite dark because I have covered it with 2 plastic roof cover to prevent the fish from jumping out. Other reason is the system is placed indoor at the laundry area at the back of the house.


With this set up, I put in 30 tails of tilapia weighing about 200 grams.

Below is a list of observation notice which are quite interesting:


1. The water is clear until today (4 Oct 08). That means it has pass about 2 1/2 weeks and we don't need to change the water.

2. I do not notice any left over food, sediments, fish waste at the bottom of the tank. It seems all of them flowed out.

3. The fishes seems to be more active and hungrier than using the normal traditional system. Every time I open the cover, all of them will rush over waiting for food hungrily. The picture below shows it very clearly:

4. The amount of food need to supply to them also seems to be more than when they are in the normal traditional system.

Water condition:


Out of curiousity, today (4 Oct 08) I did a sample test on the water's PH and ammonia content. Below is the result:

PH - quite neutral

Ammonia, 6 - 7 ppm

I got a shock really to see the result. PH looks OK but the ammonia content is very high. Strange enough is none of my fish die! The tilapia is really a tough fish.


I quickly took one set of sample from the big pond and here is the result:

PH - alkali

Ammonia - 6 - 7 ppm

Well it looks like I need to do something about the water in the pond too.

Removing the sediments

Well, it is noticed that some sediments and waste has accumulated at the bottom of the 4' fibre tank, this may be due to the following reasons:

1. They are the run away waste through the overflow pipe. The inlet of the overflow pipe was not covered initially. I quickly covered it.

2. They developed from the water which flow out of the poly tank.

We changed the water at the 4' tank (reservoir) and clean up the sediments and immediately I took another set of sample:

PH - remain neutral, slight improvement

Ammonia - slightly better, still high

Waste needs to be disposed off immediately

It looks like the system is still not perfect yet. Although I can get rid of the waste and sediment accumulation in the fish area, they are still trap at the bottom reservoir and ammonia developed. The system need to be improve further to get rid of the waste and sediment on a regular basis and it ought to be a simple job to do!

Mosquito & sediment

On the other hand, although sediment is now remove from the fish tank area, but they were found at the lower tank and in the filter. This nitrat sediment and water attract mosquitoes to breed.

Another problem encoutered is the filter and the sediment pond if not clean up regularly, they will attract mosquito to breed. Some how rather the mosquitoes like this kind of environment. The good thing about this set up is when we change the water, the downflow pipe can be temporary locked up and the pump can be stopped. Changing of water in the sediment tank and cleaning of filter do not disturb the fishes at all. This is a very good advantage as compare to traditional system whereby all the fishes have to be remove first prior to changing water or cleaning up of the tank.

Close system

Well then, there are many solutions to mosquito and sediment. One of the easier way is to have a close system with cover. The cover is required for preventing mosquito from breeding inside. The design of the filter requires an paradigm shift also. A new design is being work on.