Side question, can I get away with this micro HOB? It has predicted sponges, abs I really want something to polish the water a bit more https://www.amazon.com/AZOO-AZ13099-Filter/dp/B072KL1NDY/ref=mp_s_a_1_1_sspa?keywords=azoo+mignon+filter+60&qid=1573604390&sprefix=azoo+&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExR1dYU0xYVkVKU0E2JmVuY3J5cHRlZElkPUEwNTc5NDMwM09ETkw2WEFJM0czNCZlbmNyeXB0ZWRBZElkPUEwNDYxMzIyMTNCUVo1TExGWFgzRCZ3aWRnZXROYW1lPXNwX3Bob25lX3NlYXJjaF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl
@Sonnycbr, Instead of blindly doing water changes, you should test your pH in the cycling tank.
If it drops below 6.8, than do a water change to bring it back up above 7.0.
How much you change can depend on how it new water it takes to bring it back above 7.0 pH.
Some times, people don't know why they change water during the cycling process. They might say "Oh it is to reduce the ammonia levels". But ammonia is what feeds the bacteria. Aren't we trying to build up the beneficial bacteria? Than why are people (even on youtube) throwing out the very thing that is needed for the bacteria to colonise? The ammonia.
The real reason we change water during a cycle is because the bacteria growth/activity slows when pH drops below 6-ish. It is at it's optimum above 7.0. The new water which should ideally be above pH 7.0 (tap water usually is), will bring the ph of the whole tank back up. In addition, the new water should hopefully also contain more ammonia, food source, for the bacteria. (De-chlorinate the tap water if you use it!!)
In a tank that has been cycling for a while, the bacteria that starts breaking down ammonia will eventually remove all the ammonia, it's food source will be gone. If you don't have another source of ammonia (eg, livestock waste, degrading food, externally added ammonia) ... the newly established bacteria will start to starve. More ammonia needs to be added somehow.
The pH in a tank will naturally drop during the cycling period. The breakdown of ammonia NH3 by the bacteria leaves behind more hydrogen H. The N (Nitrogen) is removed from NH3, leaving H3. That is, more Hydrogen is left behind. The pH scale is logarithmic and inversely indicates the concentration of hydrogen ions in the water (a lower pH indicates a higher concentration of hydrogen ions).
So the water change does two things, raises the pH and adds more ammonia, not take away ammonia.
If you use RO water to cycle a tank ... RO water is devoid of a food source (ammonia) and is naturally low in pH. Is this a good type of water for tank cycling?
So now that you are armed with this information, you are now officially more knowledgeable than that youtuber you watched. Go forth and change water in a cycling tank only when needed. 50% twice a week could be the right amount for that other person, but it might not be right for you.