Separating gravel and media

[Wolf911]

I was having some trouble with my pryrolox filter not getting all the iron out after my chlorine injection stopped and I didn't catch it for a day so I decided to just spin the valve off and look into the tank. As I was lifting the valve off the rise tube came up along with it and wouldn't go back down. So I dumped the media out and the gravel came with it. Does the gravel have to be separated from the manganese dioxide before going back into the tank and how can I do that or do I have to just buy new media and gravel and start over.

I did notice before I dumped the tank that there was some gravel laying on top of the media. What's that mean?

The manual just addresses refilling with new media and gravel. The manual also says there is suppose to be laterals that the rise tube goes into at the bottom of the tank but all I found was just a basket similar to the one on the top of the riser.

The media looks good no sludge on anything in the tank so I'd like to reuse it if I can get it back in the tank.

Do you think I should soak it while I have it out in some chlorine solution, if so how much chlorine and for how long should it set.

Any help would be appreciated I've not done this before

 

[Reach4]

That has to irritate you.
You don't have to move the gravel to the bottom. It will go there on its own during the first backwash.

Pyrolox is heavy as media goes. Maybe you need heavier gravel. I also wonder if that stuff floating was some light material sucked up by the pump, but I guess that would not have made it through the top basket.

Was your top basket gunked up? I suspect it was the top basket that pulled up your distributor tube. Instead of a top basket, which can get gunked up, you might look into a diffuser.

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[Wolf911]

This stuff only lifts 2.5 inches during a normal backwash in a 8 inch tank with 10gpm. I tried separating the gravel but it doesn't really work. So your saying just dump it back in and it will sort itself out. No it wasnt gunked up. The pic is what it looks like right out of the tank no cleanup at all.
Do you think I should soak it in chlorine or just put it back together. Thanks

 

[Reach4]

I am not a pro. I would probably use a solution of Iron Out, but maybe chlorine would be better. Iron Out turns non-soluble iron (ferric) to soluble iron (ferrous). Chlorine turns ferrous to ferric, and kills bacteria.

Given the density of your media, in retrospect, garnet might have been a better choice than regular softener gravel.

Pro-OX, Filox, MangOX, and Pyrolox are brand names for solid manganese dioxide filter media.

That said, my iron+H2S filter, like yours, uses a chlorine bleach solution during each regen. So that would seem to suggest the chlorine.. My media is much lighter.

 

[Wolf911]

This stuff only lifts 2.5 inches during a normal backwash in a 8 inch tank with 10gpm. I tried separating the gravel but it doesn't really work. So your saying just dump it back in and it will sort itself out. No it wasnt gunked up. The pic is what it looks like right out of the tank no cleanup at all.
Do you think I should soak it in chlorine or just put it back together. Thanks

 

[Reach4]

You could put a few tablespoons of your media+gravel mix plus water into a capped glass jar. Shake, and see how it settles.

 

[Wolf911]

It looks to be garnet not gravel. I think I'll give it a 2 hr soak in one cup of chlorine and water and dump it back in. I d

You could put a few tablespoons of your media+gravel mix plus water into a capped glass jar. Shake, and see how it settles.

Good idea I'll try that if it settles then I'll put it all in a large container and let it separate so at least I get most of the gravel toward the bottom. The media is designed for chlorine injection so I don't think a 2 hr soak in a strong solution will harm it. I was told from the manufacturer that prolonged exposure to over 2ppm will degrade it.

 

[Reach4]

If it settles in the jar, it will settle in the tank during the first backwash. And with the higher column in the tank, I am thinking the stratification will be more pronounced. I am not suggesting pre-sorting.

6% bleach is 60,000 ppm. In my regen with a 10x54 inch tank, I use about 1/11th of a bottle of bleach during each regen.

 

[Wolf911]

Well I put the media back in after a rinsing and 2 hr chlorine soak. Even though the media backwashed clean to drain before removing from tank it definitely wasn't clean. I rinsed till it drained to the color of the well water then soaked in chlorine solution and a whole lot more came lose.

I doubt very much that the gravel is going to sink to the bottom during backwash. I tried the shake test a couple times and it's just to heavy to do much separating. It definitely wasn't the right gravel in my opinion.
I decided to put a lighter manganese coated media in as no one had the pyrolox in stock and its just to heavy even with 10 gpm in a 8 inch tank to backwash properly. Hopefully the pyrolox gravel mix will get me thru till next week when the new media arrives. The new stuff is only 88 lbs per sqft compared to the pyrolox 120 lb so I should be able to lift it as high as needed for a proper backwash. Thanks for the help.

 

[Reach4]

I suspect you may not be getting a full 10 gpm while backwashing your 8 inch tank. The cross section of an 8 inch tank is 0.349 square ft, so 10 gpm would be 28.6 gpm/ft2.

 

[Wolf911]

I never did the math but I know I'm getting 10gpm off the 3/4 inch filter discharge. Unfortunately I've pumped the backwash into 55 gallon drums more times than I'd like to count. Also I have a meter than counts the gallons less than 3 ft from the filter discharge on the main line.

Now that I've had the filter apart and saw the rise tube and the lower basket it seems to me the the backwash water probably mostly was just doing a column up the middle of the tank and maybe some along the sides. The manual talks about some lateral tubes that are suppose to be at the bottom of the tank where the riser sits on the bottom but there wasn't any there and I'm guessing they were suppose to help channel the backwash thru the media. I know shining the flashlight into the tank during backwash I could see only the edges of the media moving unlike my carbon filter where everything seems to be moving. Hopefully I'll have some better luck keeping the new lighter media clean, of coarse the chlorine pump not working for 12 hrs didn't help.

 

[Bannerman]

A distributor equipped with laterals can only be installed in tanks equipped with large 4" openings, not a 2.5" opening commonally utilized for residential applications.

The purpose for the gravel under-bedding is to function similar to a distributor equipped with lateral extensions. Since gravel does not pack tightly due to an irregular shape, backwash water entering through the bottom basket will expand outward through the gravel before being forced to flow vertically through the tightly packed and more restrictive media.

Pyrolox is extremely heavy media (120 lbs/ft3) that requires an excessive backwash rate to thoroughly lift and reclassify it. The newer media that is usually recommended and is effective is Katalox Light (66 lbs/ft3) . The usual recommended BW rate for KL is 10-15 GPM per ft2 compared to 25-30 GPM/ft2 for Pyrolox.

Also, the recommended effective Service rate for Pyrolox is only 5 GPM/ft2 whereas KL is 6-12 GPM/ft2.

Before proceeding to address any water condition issue, a full lab test is recommended to determine if there may be other conditions that may alter the treatment method(s) needed.

 

[ditttohead]

NTLWATERTEST is a great water testing company, highly recommended. Pyrolox uses garnet underneath, gravel is simply too light. The backwash rate requirement of Pyrolox (filox etc..) is 25 gpm per ft2. KL is half that. I would recommend removing the drain line flow control button during the backwash to see if you can get some good lift, then reinstall it. Garnet will work its way under the pyrolox eventually. As to the hub/lateral, they used to make a spider distributor that had flexible laterals that could fit inside a 2.5" tank opening but these failed constantly. Now we use the Vortech bottom plates.