I soon found out there are specialised articles on the market for these types of tanks, but also that they are well overpriced. I decided to use some of the leftovers to build a DIY Gravel Cleaner after the idea of JBL, found here. (Nice thing about it is that it is square so it can reach the corners of the tank easily)
This article is based on my blogpost on http://hmf-shrimptank.blogspot.com, where I also post the entire DIY project for building a filter for my shrimp-aquarium. Comments and feedback are welcome!
Here are the steps I took:
Step 1: Ingredients
Some tubing of roughly the same diameter
Have some tie-wraps and teflon-tape or plumbers-tape ready
Take a small (transparent) square container left over after the contents have run out. I used a soap-container in my example. I would not recommend to use something that stored any more serious chemicals
Clean out the container REALLY thoroughly as shrimps will die if you don't!!!
Step 2: Building
Bend the PVC pipe in a 90 degree angle to form an L-shape, such that it feeds the hose away from the aquarium. Bend the pipe easily by pouring hot water over it
Insert the PVC pipe into the fill-cap of the container. If it doesn't fit, use the plumbers-tape to create a tight fit and secure it with a tie-wrap
Fit the hose over the other end of the PVC tube by heating it in hot water, lubricating it with some soap and stretching it over the PVC pipe. Cool it down in order to quickly reshrink it and secure it with a tie-wrap
Do some cleaning again to make sure any leftovers of soap are gone!
Step 3: Usage
Place a bucket on the floor near the tank
Put the gravel cleaner in the tank (make sure there are no curious shrimps in it)
Suck up some water from the other side of the hose (don't worry, you won't die of a little water and you will get better at it)
Now quickly put that end of the hose in the bucket when pressure builds up
If you have a large diameter hose, like I do, squeeze it to control the flow and keep the gravel inside the tank
To stop the flow, just pull the cleaner out of the aquarium
Step 4: Tips
I actually use the same hose, but in reverse, for filling the aquarium
The larger the difference in heights between the bucket and the tank, the higher the flow-rate
Have fun using this cheap solution to great aquarium cleaning!