Not exactly and experiment, but....

[drdale]

I am a first time user of a reverse flow (in this case freshwater) under-gravel filtration system in 75 gal planted aquarium.  So far the only issue is the suspension of very fines in the water column.  One factor in this is the flow rate through the gravel substrate.  Using manufacturers data, I estimated the flow as somewhere bertween one-half and a whole gallon per square inch of substrate, about 2 inches of medium size pea gravel.  Of course, the gravel texture, how clean it is, the pump's 'head,' tubing sizes, etc all potentially make a difference in flow rate.  However, in all my searching, I can not find any mention of recommendations for (forward or reverse) flow rates for under-gravel filtering.  Which leads to my question, have any of you out there seen reputable information published or on the Internet about under-gravel filtering flow rates, substrate density, timing for such filtering to "mature," etc., for this user?  Of course, if so, I appreciate a shout out, especially if you could cite the source, but even if y ou only remember some infromation from "somewhere," I'd still be interested.  Thanks, guys and gals of the forum.

drdale

[TheSwissAquarist]

Good Luck and keep us posted!

[drdale]

Thanks to the Swiss guy with MTS, albeit my opinion is that MTS is not a disorder of any significance.  🙂

drdale. 

[TheSwissAquarist]

On 10/7/2022 at 8:23 PM, drdale said:

Thanks to the Swiss guy with MTS, albeit my opinion is that MTS is not a disorder of any significance.  🙂

drdale. 

🤣

[Gwallace]

When I started in the hobby 45 years ago (yes i'm old!) UG filters were used extensively.  And yes some people used them in reverse along with some type of mechanical filtration to polish the fines out of the water column.  I have never seen any reliable data about flow rate.  Due to the tremendous number of variables I don't think you will ever really know the actual flow per square inch.  Estimates of UG flow rate abound but no verifiable data seems to exist.

I still use UG filters in several tanks though I use them in the traditional manner and only consider them "bio" filters.  

Good luck in your quest!