HOW MUCH TENSION ON THE NET?
What makes me address the issue of "poor tension" on the table tennis net is some slow-mo video as taken during ITTF World Tours, from that you can clearly see the net cord trembling and swinging strongly up-and-down upon the ball impact, that bespeaks a very poor tension is put on the net cord.
Admittedly, a slack net cord will give a huge advantage to the less skilled player. It is unfair, it is not acceptable anyway, you understand.
As is a common knowledge with experienced table tennis folks,
"It is better to have the net cord over-tight than over-loosen ", as it is against the Rules to let the net cord trembling and swinging while a rallie is on.
HOW DO I CHECK THE NET CORD TENSION ?
-- Let the standard 100 gramme gauge hang freely on the mid of the net cord using the 14,25 notch , and see if the gauge's bottomside touches the table surface. If it does, the cord is unduly slacked. Handbook For Match Officials, 2014 wrote:
PLAYING CONDITIONS.
5.5 It is important for the umpire or assistant umpire to check both the height of the net
and the tension of the net-cord. This should be done prior to every match, including
team matches within a team competition. It is not really satisfactory just to estimate
the tension by finger touch and several manufacturers have produced weighted net gauges,
which ensure consistency. These gauges, which weigh exactly 100g, have two notches,
one at 15.25cm and the other 14.25cm. The weighted gauge should only be
used to check the tension – it is not advisable to use it for checking the height.
After the height has been checked using a plastic net gauge, the "weighted" gauge is rested
on the top of the net, in the centre, and the tension adjusted until the bottom of the gauge
just touches the playing surface. If necessary, quickly recheck the height at each end after
the tension has been adjusted. Do not use the plastic gauge and "weighted" gauge at the same time.
Also, when checking the net, it is important to ensure that the clamp is attached as close as possible to the table.
Ensure that there is no cord hanging down from the net post which could affect the ball or distract the players.
Be happy.