Greensand filter: actual brine draw seems super short?

[Rainking430]

Kind of new to self servicing our home's water systems. Water quality has been great but one thing about the greensand filter has me wondering. The current setting for the Brine Draw cycle is for it to run for 1 hour. However, the actual draw of the potperm lasts only like a minute and a half, then I hear a big clunk (I think from the brine tank valve closing) and the draw from the tank stops. The tank itself looks fine otherwise, from what I can gather from research it appears to hold the correct amount of brine (water line being about 3/4"-1" above felt). And I can actually feel it through the line that it is pulling the chemicals during that minute and a half or so. Still, it just runs for the BD cycle for the rest of the hour, and I don't see much purple come out the drine line during this time, but the water is much clearer.

What confuses me further is that years ago when we first installed it, the system didn't seem to be so quick to pull all the potperm from the brine tank, and the drain line would run real purple for a bit until it flushed everything out during the full BD cycle. That made it feel like it was doing a more thorough job then than it is now.

So my question is, is this minute and a half of draw from the brine tank normal? And if so, is keeping it set to one hour for the whole BD cycle still good just to make sure any excess potperm is flushed from the system?

If it is not normal, could it be the BLFC flow is too much? I think it was replaced at some point. Looks like what's on there is a 1.5 gpm BLFC

Thanks everyone.

PS - also if it helps, it's a 10" tank with a Fleck 2510SXT head

 

[Reach4]

Not familiar with your pot perm system. Sounds interesting. How big is your tank that holds the pot perm, and how frequently do you need to add pot perm? How frequent is the regen (DO setting)?

I would guess that your pot perm tank is 15 gallons or less -- much smaller than a softener brine tank.

If you can sample the drain line water 30 minutes into the BD cycle, and it tastes good, then you could probably reduce BD to 30 minutes.

Pot perm when concentrated is caustic. I am not a pro, and maybe tasting is not a good idea. I probably would, but that does not make it safe.

 

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[Rainking430]

The brine tank for this greensand system is only about the size of maybe a 5 gallon bucket. It's this one: https://store.afwfilters.com/chemic...systems-potassium-permanganate-potperm-kmno4/

And the regen runs every 3 days. we tend to have very hard water here (west of Jupiter, FL)

To add: I don't have to refill the potperm but every 2 months or so I think. But it's a big 4.75 lb bottle.

 

[Reach4]

Interesting. So the solution tank (what that container is called) is good for about 20 doses. I wonder how they shut down the flow after about 1.5 minutes.

I would be interesting to see the current settings. You would probably like to have that on record anyway, and once you got that, it would be nice if you posted the settings.

When you do refill the potperm solution tank, do you use one bottle, and top up with soft water?

 

[LLigetfa]

If you can sample the drain line water 30 minutes into the BD cycle, and it tastes good, then you could probably reduce BD to 30 minutes.

Is not pot perm poisonous? I would not taste it.

 

[Reach4]

Is not pot perm poisonous? I would not taste it.

I understand. Chlorine is poisonous, but millions of people not only taste, but drink a weak chlorine solution daily.

The thought is that after a lot of slow rinse, the pot perm should be at a very low level.

Strong chlorine solutions have a smell, so that could warn you. Potperm has a strong color. I don't know how poisonous a solution too weak to see color would be. SenSafe offers test strips. https://sensafe.com/sensafe-permanganate/

Maybe use strips to monitor the drain line after 10 minutes, 20 minutes, etc.

 

[Rainking430]

Interesting. So the solution tank (what that container is called) is good for about 20 doses. I wonder how they shut down the flow after about 1.5 minutes.

I believe there is a float at the bottom of the intake valve, unlike with other systems. So the float lowers as the brine tank empties until it finally shuts the valve. At least that is how I envision it.

I would be interesting to see the current settings. You would probably like to have that on record anyway, and once you got that, it would be nice if you posted the settings.

I will try to get that for you.

When you do refill the potperm solution tank, do you use one bottle, and top up with soft water?

I do drop in the whole bottle, but do not top up with additional water. I thought I read somewhere in the documentation recommending against adding more water when adding chemical. That said, your question now has me thinking if it might be better to add less chemical more often.

As far as testing the water mid BD cycle, yeah not going to taste it lol, but I may test it in other ways. And yes, you can definitely smell it in otherwise clear water if the concentration is too high. I've also seen reports of serious health issues if it is not fully flushed out of the system, so I guess it could make sense if the BD cycle were to seem absurdly long, just for safety reasons.

 

[Reach4]

I believe there is a float at the bottom of the intake valve, unlike with other systems. So the float lowers as the brine tank empties until it finally shuts the valve. At least that is how I envision it..

Maybe the BF is non-zero, and it adds water at the end of the regeneration. Try checking the liquid depth after each regen.

 

[Rainking430]

Maybe the BF is non-zero, and it adds water at the end of the regeneration. Try checking the liquid depth after each regen.

Correct, the full regen is of the backwash > brine drain > rapid rinse > brine fill type. And when it brine fills it only adds enough water to cover the felt/potperm plus maybe an inch or even less. According to the documentation I have that is spot on. Which is why I wonder now whether the replacement BLFC could be causing it to drain the brine too quickly? I recall that it was a guess as to what size was originally on there, so they used a 1.5 gpm one. I'm wondering now if that should instead be a .5 or 1.0 BLFC?

 

[Reach4]

That felt thing is a new concept to me. That's interesting and useful I think.

Injector controls draw rate. If you have an air check valve, once the liquid down to the middle of the air check valve pickup, the remainder of the BD cycle serves as a slow rinse to move the bolus of potperm solution thru the media in a laminar flow.

A 1.5 gpm DLFC is more than I would think, and I don't remember seeing that size. Did you look at the rubber button. Was the molded number opposite the F 123 by chance? Oddly enough, that is 0.125 gpm.
BLFC controls the fill at the end.

 

[Rainking430]

BLFC controls the fill at the end.

This is really good to know actually, and corrects my previous assumptions (see, told you I was new at this). The BLFC was definitely replaced, as it was leaking during the regen process. Nothing else has been touched, so I am less concerned now that it may be drawing quicker than it used to.