Microscopic View of White Pumice
Channel: Pondguru
Date: 2023-03-11

#shorts A 300x view of White Pumice (Lava Rock)
http://www.filterpro.co.uk
Pumice is a strange one as it is regularly promoted as a cheap 'DIY' filter media while at the same time a small dense grade of pumice is sold under a brand name for a high price (as something special). 
People can't seem to recognize that they are both pumice, just different sizes and different grades.
The  grade of pumice in this video is very good since it is highly porous, light and has a decent amount of variability to the internal structure - this is simply sold as 'Pumice' for use in koi shower filters and sumps.
The smaller more dense type sold under a popular brand name (which often contains a lot of junk grey and black rock) has a much more dense internal structure so is way too dense to be of much use, hence the 'manufacturer' recommending a flow rate of only 50 US GPH to allow it to support anaerobic bacteria - at that point the filter is practically a slow flow nitrate reactor. That low flow rate is not feasible in most aquarium or pond filters.
If you're going to buy pumice get the ordinary white pumice as it is much more porous and approx. 10x cheaper than the branded pumice sold in aquarium stores.
White pumice generally has a specific pH or around 8.0 so is more suited to use in koi ponds and aquariums with fish preferring a higher pH with good mineralization in the water (e.g. African cichlids, livebearers, goldfish).
Since pumice is a natural rock it is impossible to work out the surface area per liter / per kilo since every rock differs from each other - some is good (very porous) and some is not so good (more dense) and many of the tunnels and bubbles inside the rock are sealed causing some pieces of natural pumice to float.

When ammonia, nitrite AND nitrate is processed it is a full cycle. 
Most filters and filter media only allow for half a job which results in high nitrates which have a long term debilitating effect on the fish .
The eyes don't lie and when you get a zoomed in view of filter media you can make your own decisions......why do no other channels show INSIDE filter media they (are often paid to) promote?
Because "trust the science". 
Nope, trust what you see.
Full video here: https://youtu.be/QTtAUYR67Eg
A guide to how much media to use for various stocking scenarios to achieve a FULL CYCLE can be found on the Q&A page of the FilterPro site: http://www.filterpro.co.uk as well as lots of other useful information.
Avoid using conditioners which bind / detoxify / remove ammonia, nitrite and nitrate as they prevent bacteria populations from thriving (by starving them). A normal water conditioner makes the water safe for life and allows the bacteria to achieve a full population in line with the available food.