Maybe you've posted this already in another thread, otherwise the question should be how long has the tank, and especially the filter (and/or media), been set up? Or how long have had the sand and rocks in there? Also, what size tank? Have you added fish recently? If any of it is recent the best answer may be to give everything time to settle down and balance out rather than fuss with it too much.
Visual water glass test doesn't necessarily eliminate a bacteria bloom as the problem, heterotrophic bacteria (the type you actually see in a bacteria bloom) can multiply and/or disappear quickly, depending on conditions, especially so in the small volume of water in a drinking glass. If it turns out it's tiny water bubbles from your tap water, your
tank should also clear fairly quickly and the answer isn't cleaning, changing, or adding filtration-- the exception being if your filter itself is the source of micro bubbles, in which case you should be able to see them coming out of the filter.
Unless your filter is mature and has been running a while, I wouldn't be cleaning it yet or changing media, etc. If it has been running some time I still wouldn't be too quick to clean it if flow is still good and media looks clean. Otherwise I would clean it gently (with tank or well water, not chlorinated tap water). Whether a new or new-
ish tank/filter, or an established tank going through bacteria bloom or mini-cycle, sometimes you can be your own worst enemy by getting too zealous to fix it-- cleaning, water changes, water clarifiers, micron filters, adding filters, etc.-- when sometimes your best option is to leave it alone and allow time for things to settle down and come into balance.
I learned this years ago from personal experience, but so you don't take my word for it, here are a couple of references:
Link
A water change is not recommended to clear a bacterial bloom. When the free-floating heterotrophs are removed, the others will reproduce even faster to compensate, thus worsening the bloom. If left alone, they usually dissipate in a few days. In an established tank, however, the source of the problem should be removed. Clean the gravel, remove decaying matter, don’t overfeed, reduce overstocking, etc. And be aware of the oxygen shortage issue.
Link
Larger, irregular water changes may actually end up causing more harm than good by suddenly altering the tank’s chemistry to an excessively large degree.
Leave the tank alone. Stop feeding the fish for a week, as healthy fish will be fine, and don’t clean the filter or carry out any more changes for at least a week.
Stop feeding is optional, more of an emergency measure in my opinion. You can do just as well to continue feeding, but lighten up some. What you're trying to do is get your tank to settle down and balance out with beneficial bacteria, bio-load, chemistry, etc. Stopping feed for a week, then suddenly feeding again as normal doesn't necessarily accomplish this.
On the other hand, if it's a mature tank and you have lots of gunk in the filter or substrate, cleaning them would be one of the first steps. (actually your sand looks clean, possibly new, in the photo).