
7 months is a not a very long time but A LOT have happened during these 7 enduring months.
Well the good news is the tank is stable more or less and I have managed to reduce phosphate to near zero and nitrate down to less than 10 ppm.
The bad news are: I had a small electrical fire due to a loose up pump pipes that squirted salt water everywhere, I had a disease break out that wiped out all but one fish, and there was COVID 19.
Prerequisite: Plumbing Skills
I must admit I have zero plumbing skill. And it cost me dearly. The up-pipe to the overhead sump was not secured enough and it came lose one day while I was at work.
The pump pumped almost 40 liters of salt water into the air! In the process it soaked the cooling fan, the lighting, wet the floor and sofa, wet the power socket and caused an electrical fire and tripped the circuit breaker and there was no power in my house and the children were running riots. All these while I was at work! I received an angry phone call from my wife and was told about it. I had to “teleport” back from work immediately my wife threatened or that will be the last of my hobby.
And so I had to ditch the overhead sump, or any other filtration methods that would involve any form of plumbing.
Fluval C4 HOB
If you, like me, do not have the luxury or budget or plumbing skill to deploy a sump and had to choose a conventional aquarium filter, go HOB. I know there is the canister option but DON’T! For marine tank, the sponge used in aquarium mechanical filtration is a nitrate factory. And you will want to get nitrate down to a very low level if possible. You can read more here about how sponge will become a nitrate factory.

With a HOB you can quickly swap your sponge filter every few days with a cleaned one. I switch between two sponges. I would take the old one, rinse it under high pressure water, and put it out to dry under the sun if possible.
I had wanted an AquaClear HOB as it allows the most space to house chemical media but it was rare to find one these days.
Alas, I settled for a Fluval C4 HOB. It is rated upto 70 gallon or 265 liters. My cube is 24 gallon or 100 liters. It worked out perfect. And somehow it is strange that not many HOB filters are rated for marine aquarium, and Fluval C series is rated for marine.
As A Chemical Media Container
The reason why I chose to use a HOB filter is purely as a container for chemical filtration. I cannot think of another way to send water through carbon and phosphate reducer. I did not use any media ring this time. I had a bag of phosphate remover, a bag of activated carbon, and a bag of Purigen in it. And there was still room for more though.
Technically, you will not want a sponge with floss on it as it will trap the planktons and whatever copepods in the water. These are food for fishes and corals.
I also learned that in marine aquariums, you can do away with any form of mechanical filtration! Just need to vacuum the substrate.
Great Air Water Exchange
The HOB also adds as great air and water exchange beside the protein skimmer. Different from a planted tank where plants can provide oxygen to a tank inhabitant, in a marine tank, there is no plant to provide that and you do not want to have an air stone in a marine tank, trust me. Bursting bubbles caused spurting and it will cause a lot of things to corrode.
Fan Cooling
As my set off point was to be on the cheap end of the scale, I did not have a chiller to begin with. The weather here in Asia is killing a lot of stuffs in the water, including turbo snails and Zoa.
Without a chiller my water is consistently above 29 degrees Celcius (84 F). After adding a cooling fan I managed to lower the water temperature to a around 26.5 degrees Celcius (79 F).
Not a placebo effect
Using a cooling fan is NOT a placebo effect. It is based on the theory of thermodynamics under endothermic process. Basically, water takes heat away when it evaporates.
I also took this opportunity to experiment with different sizes and different fan speed. And to my surprise, the size of the fan did not affect the temperature at all. They all stayed around 26.5 C! hmm… I’m not a student of thermodynamics but apparently there is a threshold that once reached no more water can evaporate and thus the temperature cannot be lowered further by evaporation.
With evaporation comes lowering of total water volume in the tank. It will be a constant effort for you to keep topping up your tank water. And remember, the water that evaporates are pure water. The salt and other minerals stay in the water!
And as a result it will increase the salinity of your water! As such, you need to top up with exactly the same amount of water that was lost to evaporation.
Types of ATO System
I am losing about 2 liters of water everyday due to evaporating with a cooling fan. I was topping up water first thing in the morning, and first thing I return home from work. This is not ideal!
And I needed a solution. A automatic water top off system that can take care of the constant topping up of water a.k.a. ATO System.
Mainstream ATO
The typical mainstream ATO system is expensive. It goes in the region of hundreds of dollars, cheapest in the region of USD80. It is basically a water level detector with optical or mechanical sensors.
You place the sensor at a desirable position and once the water level drops below that level it will activate a pump to pump fresh water from a reservoir into the display tank.
Prices will depend on how elegant you want the ATO to be.
Cheaper mainstream ATOs have bulky sensor, but most of them are meant to be hidden in the sump area. For AIO system you will need to live with a sensor with wiring some where in your display tank.
Float trigger ATO
A cheaper solution is to invest in a gravity fed ATO with a mechanical float. The float will be triggered when water level drops. Gravity will push fresh water down.

Again, these are meant for sump tank with a cabinet to hide the float and reservoir. But if you have a AIO tank like me, a float in your tank look kinda like a toilet.
Gravity Fed Bottle/Bucket
This is the cheapest ATO in the market. Ranging from USD10 to USD30. But they are not meant for larger tank as the amount of water these ATO can hold is very limited. You will end up topping these bottles several times throughout the day.
If you have a micro tank, you can have one of those bucket/bottle fed ATO system. They had two tubings. One tubing allows water to enter the tank. The other tubing will allow air to fill the void created by water entering the tank.

So when the air intake tubing is touching the water, no air can enter the reservoir and so no water will enter the display tank. When water level drops exposing the air intake tubing, air can enter the reservoir and fresh water can then flow into the display tank until the water level covers the air intake tube which will also stop the flow of fresh water into the tank.
There is an underlying problem with these ATO. They are based on the fact that as long as no air can get into the bottle, no water can enter the display tank. So what if the bottle neck seal developed a leak?
Plant Watering Timer: Auto Top Off System Alternative
to be continued…