Clearing particulate cloudiness

A cloudy aquarium due to substrate change or addition. Image from a member of the forum at the Reef2Reef website –

I have posted about this before. Tank cloudiness due to high particulate concentrations is common when changing substrates or adding substrate for the first time. It is also an easy problem to solve. To do so you have a few options, listed below in no certain order. NOTE: It’s worth mentioning that cloudiness due to bacterial blooms and such require a different solution. That’s a post for another day. 

  1. Let your existing filter(s) do the work
  2. Add a new, temporary mechanical filter
  3. Do nothing and wait for the particulates to settle

Beginning with number one above, your existing filters can certainly be used to remove the particulates. To help your filter(s) accomplish this, the easiest solution is to add extra mechanical filtration. Commercial products like Seachem’s Purigen can help clear normal, fine organic particulates. However, Purigen is not the best at clearing high concentrations of dense, inorganic particulates. There are commercial aquarium products for this too. One of the best is filter floss, sometimes referred to as “batting”.  You can you use polyester fill like what is used in pillows, which is available at most home stores (e.g., Wal-mart, Target). For the polyester pillow fill, just make sure it’s not treated or coated with anything. The floss should be placed where water first enters the filter. This will ensure that particulates, especially larger pieces, don’t clog up your bio media and chemical media (if you’re using that). Using this method and depending on the size (gph) of your filter(s), the tank should be cleared in less than 24 hours. 

Number two above is another option. The advantage of this method is that you don’t have to make any changes to your primary filter(s). There are multiple ways to add new mechanical filtration. You can add an existing OEM (original equipment manufacturer) filter that you have lying around or purchase a new one. You can also build your own, which is quite simple. See my posts on a DIY solution for removing particulates and DYI small filter.  Adding additional mechanical filtration should also clear the tank water in less than 24 hours, assuming you have an appropriate filter size. In other words, don’t expect a small filter (e.g., Aquaclear 20) alone to clear a 150g tank very quickly. 

Making your own filter is really simple and gives you lots of different options. In fact, I used the DIY option to clear a 40g breeder tank earlier this week. The tank contained a gravel substrate, which I removed and replaced with sand. Though I washed the sand thoroughly beforehand, removing the gravel and adding sand still created some cloudiness. I stuffed some filter floss into a condiment bottle (described in the two links above), hooked the bottle to a small submersible pump, and then dropped it into the tank. The tank was crystal clear the next morning when I checked on it. 

The last option listed above is to just let the particulates settle on their own. Of course, the time required to do this will depend on the amount of cloudiness, the size of the tank, the amount of your existing filtration, etc. If you’re setting up a new tank and it’s cloudy, let the “dust” settle before adding your regular filtration. This way you don’t clog up the filter with all of the particulates (unless you set the filter up initially to filter out the particulates and then are planning on cleaning it out and adding your normal filter media).  

If you’re setting up a new tank with substrate and the tank is really large, you’ll need a pretty large filter in terms of gallons per hour (gph) to clear it quickly. You can put together a hefty DIY filter for that purpose. The Versafilter I created to clear a 75g a few years ago did the trick in less than an hour. 


Leave a Comment