Fluid dynamics/Air pressure physics question. Poop related.

[grebo]

Ok, so my cesspool is failing.  Filling up and leaking all over the ground.  Nasty.

So I do some research and find out that the likely cause is too much "Bio-Mat" clogging up the soil.  Anerobic bacteria secrete this crap and over the years it builds up alongside grease and shit around the tank until water cannot percolate thru anymore.

Do some more research and find this guy:  http://www.septicgenie.com/  He makes a product that basically pumps air and bubbles it thru the tank, sort of like a big septic aquarium pump.  The air makes anaerobic bacteria die and super invigorates the aerobic bacteria which happily eat all the biomat.  He charges $2,000 which is super cheap compared to tearing up the yard and paying $25000 or so, but not cheap enough for broke ass me.

I think to myself:  Self, I can build my own with some PVC and an air pump, in about 2 hours, so why pay 2 grand to that guy?  Only problem, what pump?  Is an aquarium pump going to be able to pump air thru 1/2" pvc under 10' of water?  I don't know any of the formulas and stuff for it, can't seem to find out how to do in online either, does anyone on here have any insight??

I'd appreciate any help, thanks!

Edit:  Title revision.

[Yegolev]

Air compressor?

[grebo]

Air compressor?

Yeah, I thought about that, it certainly fulfills the low volume, high pressure side of the equaition.  Only things are, I don't know how a compressor would like continuous operation for months, and it is likely to be super freaking loud. 

I think I need some kind of super aquarium pump or an industrial air pump of some sort.

[Yegolev]

Not sure where you will get a quiet version of those... months?  I guess if you have a small pump it will take a while to push oxygen into the biomass...?  Have you tried that enzyme shit you can get at Home Depot that you flush down?  Might be too late for that.

Hell, if it's just oxygen that's missing, seems like you could just crack the lid for a while.  Of course that has other side-effects.

[grebo]

If a company makes a product, prints "septic" on the label, I've probably tried it in the past couple years.  Lye works for a little while by turning fats into, well, soap,, but it kills bacteria.  The best thing I've tried so far is Chloroben Aid-Ox, basically 9lbs of oxy-clean.  If I use all 4 bottles (about $160) it fixes the problem for a good month.

I have left my biology degree in my other pants, so forgive me if I get this a bit wrong, but what I think happens is:  The Aerobic bacteria use up all the oxygen in the water doing their thing eating waste and reproducing, so they start to die off and can't really do enough work to keep the system working.  Anerobic bacteria flourish in the deoxygenated water.  Adding more air to the water should, theoretically, change the whole dynamic and make it work more betterer.  I'm going to try it anyway.

[Yegolev]

Change your diet? 

[apocrypha]

If it goes hilariously horribly wrong and you end up covered from head to toe in a fine particulate spray of shit and biomat can you post pics? 

Seriously though, you say that it's the soil around the tank that's clogged up, so is bubbling air through the tank itself going to solve that? Don't you need some way of clearing the drainage field of, well, crap?

[bhodi]

Well, you can look at the size of that pump and see that it's not that big. Watching the 'see it work' video shows that it's got quite a good amount of volume. I would look at maybe a sump pump or, if you can find it, some super large aquarium pump that cleans 500 gallon tanks.

The tricky bits look to be that big item that goes into your tank itself, as well as that bacteria powder (which you'll need) It does look like just a bundle of plastic tubes glued together, with a spacer on the bottom to give flow around it. If you do it yourself, you probably want to copy the design. I wouldn't know where you'd get the bacteria.

[Trippy]

Post this question in a plumbing forum.

[grebo]

If it goes hilariously horribly wrong and you end up covered from head to toe in a fine particulate spray of shit and biomat can you post pics? 

Seriously though, you say that it's the soil around the tank that's clogged up, so is bubbling air through the tank itself going to solve that? Don't you need some way of clearing the drainage field of, well, crap?

Yes, definately pics.  I wanna be a headliner on failblog.

I believe that it will work because it will create an environment that aerobic bacteria will thrive in, and apparently those are the ones that eat and get rid of the grease/paper/crap/biomat/everything.

Now who works at SeaWorld and can tell me what kinda pump I need???  

[grebo]

Well, you can look at the size of that pump and see that it's not that big. Watching the 'see it work' video shows that it's got quite a good amount of volume. I would look at maybe a sump pump or, if you can find it, some super large aquarium pump that cleans 500 gallon tanks.

The tricky bits look to be that big item that goes into your tank itself, as well as that bacteria powder (which you'll need) It does look like just a bundle of plastic tubes glued together, with a spacer on the bottom to give flow around it. If you do it yourself, you probably want to copy the design. I wouldn't know where you'd get the bacteria.

I figure I can fake the big item just by building a T out of PVC, capping the ends and drilling some small holes in it.  Should work about the same.

Bacteria thing may be tricky, I will probably just make the thing, run it for a while and see what happens.  If it's not working that well, I can just go get any of a dozen commercially available bacteria products, dump it in and hopefully that will jump start it.

I will probably go post on a couple plumbing type forums, just figured somebody on here might be able to solve the whole "how much PSI do you need to force air underwater" type problem.

Thx for the responses.

[FatuousTwat]

Ok, so my cesspool is failing.  Filling up and leaking all over the ground.  Nasty.

So I do some research and find out that the likely cause is too much "Bio-Mat" clogging up the soil.  Anerobic bacteria secrete this crap and over the years it builds up alongside grease and shit around the tank until water cannot percolate thru anymore.

Do some more research and find this guy:  http://www.septicgenie.com/  He makes a product that basically pumps air and bubbles it thru the tank, sort of like a big septic aquarium pump.  The air makes anaerobic bacteria die and super invigorates the aerobic bacteria which happily eat all the biomat.  He charges $2,000 which is super cheap compared to tearing up the yard and paying $25000 or so, but not cheap enough for broke ass me.

I think to myself:  Self, I can build my own with some PVC and an air pump, in about 2 hours, so why pay 2 grand to that guy?  Only problem, what pump?  Is an aquarium pump going to be able to pump air thru 1/2" pvc under 10' of water?  I don't know any of the formulas and stuff for it, can't seem to find out how to do in online either, does anyone on here have any insight??

I'd appreciate any help, thanks!

Edit:  Title revision.

I'm gonna go grab some popcorn... And a poncho.

[Abagadro]

Dug up this little article discussing head pressures and such. Might be useful to you.

Here is the book they reference for getting specific on such things. It looks like a textbook. If you are near a university, you can see if they have it or if they will Interlibrary Loan it for you.

[Abagadro]

I also found this product which is not cheap at 650 bucks but certainly better than 2 grand. It may also give you some ideas on how to build one yourself in a different manner.

[grebo]

I also found this product which is not cheap at 650 bucks but certainly better than 2 grand. It may also give you some ideas on how to build one yourself in a different manner.

That looks like a winner!  I'm gonna get me one, I'll let you all know how it works.  Maybe I'll even take pictures.

[schild]

I've never felt there was a thread that didn't deserve some kind of picture.

Until this one.

[UnwashedMasses]

Are cesspools up to code where you live?

In my current state of residence (Mass), you can't even sell your house with a cesspool.  Don't ask me how I know.

You may be throwing good money after bad; although a septic system will cost you $$$$$.

[Salamok]

I've never felt there was a thread that didn't deserve some kind of picture.

Until this one.

so yer not dying to see how this shit turns out?

[grebo]

Are cesspools up to code where you live?

In my current state of residence (Mass), you can't even sell your house with a cesspool.  Don't ask me how I know.

You may be throwing good money after bad; although a septic system will cost you $$$$$.

I also in MA.

You can't sell new construction, or upgrade existing, or change use with a cesspool, but you can transfer ownership of existing property with one, so long as you passed title 5 within the past 2 years.  So sez the lawz anyway, as I read them.  Please point to where I'm wrong, if I am.

[Baldric]

An actual engineering question on F13 who knew.  Anyhow, what you would need is a blower that has a discharge pressure of around 12 to 15 feet of water or 150-200 inches of water and flowrate of around 5 to 10 SCFM.  You should be able to find a Grainger Supply in your area for the blower. 

One word of caution, if you use an air compressor and the discharge pressure of your compressor is greater than 70 ft of water or 15 psi DO NOT use PVC pipe because you are risking explosive decompression.   

[apocrypha]

explosive decompression.   

Those words in a thread with "poop" in the title must surely presage some kind of legendary event.

[squirrel]

I've never felt there was a thread that didn't deserve some kind of picture.

Until this one.

so yer not dying to see how this shit turns out?

I lol'ed. Poop funny!

[grebo]

Hey, so, progress!

I posted this problem around on some other forums and asked a few engineer friends, but nobody I spoke to last year seemed to have a clue about how to find a correctly sized pump so I kinda gave up on it over the winter...I threw in the Aid-Ox a few times and kept it up that way.

About a month ago I had a bit of extra money and decided that I really needed to fix this in some semi permanent fashion, so I started googling around again, ended up at a physics page describing the method for calculating the water pressure at a certain depth in pascals.  Then I found another page that gave the conversion into PSI, then I hit on the genius notion of looking for air pumps for ponds!  I found these guys who had the lowest price on a Pondmaster 100 that put out enough PSI to force air under 11' of water, more than sufficient for my needs.

I got the pump, some PVC pipe and elbows, and built my snorkel to stick in the tank, got a rubbermaid container to put the pump in outside and built this:


The pump was $140ish with free shipping, the PVC pipe I had left over, the elbows and container were maybe $10 more.  That's about as much as Aid-Ox costs for 4 months or so... if this works I saved a ton of money.

So far, it looks just like the Aid-Ox looks.  I think I should probably get a reducer valve as there is quite a bit of air going into the tank, but for the first couple days it should be fine...  I'll post some pics when/if it clears up the problem.  I plan on adding a timer to the setup after things get working right, I'm hoping I only need to run the pump for maybe an hour a day...

[MahrinSkel]

It may be too late to offer this suggestion, but what came to mind as I read your description of the base problem (getting lots of little air bubbles in your septic tank) was irrigation drip pipe.  Get a 2 foot length of cast iron or steel 6" pipe, drill some holes in it, wind 50-100 feet of drip pipe around it and use cable ties to secure the drip pipe through your drilled holes.  Hook that to a heavy-duty garden hose connected to your air pump, lower it to the bottom of your septice tank (maybe use a plastic-sheathed wire cable for load-bearing so you aren't having to worry about the hose degrading to the point it parts and drops the whole thing to the bottom, unrecoverable), and what you've got is a low-tech, low-cost, small scale activated sludge process diffuser.  Note that activated sludge can create what amounts to a nasty version of pond scum on the top layer of your septic tank, but I suspect turning the aerator off for a few weeks would break that up, and if it's only running part time I doubt it will happen.

If your PVC "T" isn't oxygenating enough (because the bubbles are too big and it's just stirring it), you might try again with my method.  Pretty sure an hour a day with something like this would be more than enough aeration.

--Dave

[grebo]

This sounds like a horrible idea.  Especially when you factor in your costs in material, time, and uncertainty (you don't seem to have much technical experience in this matter, so it very well could be all for naught).  


People, I've said it a thousand times and I'll say it again:  when you're not at work, you're still on the clock.  Everyone is worth X amount per hour.  Even if you're salaried, you can figure out what the FMV of your services are per diem.  So when people do things like drive 20 minutes across town because gas is 4 cents cheaper, or wait in line all day for a free burrito at the grand opening of Taco World, Or attempt an elaborate and exotic do-it-yourself septic tank fix, what they're really saying is that they're not worth anything.


Have some self-respect people.

Bah, humbug.  I did a bunch of reading on products that are out there that essentially do the same thing I'm doing, add air to the water.  They all want lots of money, I spent way less to do basically the same thing.  AND if I can fix failing septic systems for sub $200, there may just be a market for that.

[grebo]

It may be too late to offer this suggestion, but what came to mind as I read your description of the base problem (getting lots of little air bubbles in your septic tank) was irrigation drip pipe.  Get a 2 foot length of cast iron or steel 6" pipe, drill some holes in it, wind 50-100 feet of drip pipe around it and use cable ties to secure the drip pipe through your drilled holes.  Hook that to a heavy-duty garden hose connected to your air pump, lower it to the bottom of your septice tank (maybe use a plastic-sheathed wire cable for load-bearing so you aren't having to worry about the hose degrading to the point it parts and drops the whole thing to the bottom, unrecoverable), and what you've got is a low-tech, low-cost, small scale activated sludge process diffuser.  Note that activated sludge can create what amounts to a nasty version of pond scum on the top layer of your septic tank, but I suspect turning the aerator off for a few weeks would break that up, and if it's only running part time I doubt it will happen.

If your PVC "T" isn't oxygenating enough (because the bubbles are too big and it's just stirring it), you might try again with my method.  Pretty sure an hour a day with something like this would be more than enough aeration.

--Dave

Awesome idea.  I think I'll end up doing this, will allow me to hide the pump under my porch and will eliminate any obvious things sticking out of the tank for people to drive by and notice.

There was an "aerator" that came with the pump , basically a plastic pvc end with about 20 little jets, I don't have just the pvc stuck in the tank.  Your idea sounds way better tho.

Edited to fix my stupid quote mistake.

[gryeyes]

Becoming mechanically proficient will pay dividends for your entire life.

[MahrinSkel]

Awesome idea.  I think I'll end up doing this, will allow me to hide the pump under my porch and will eliminate any obvious things sticking out of the tank for people to drive by and notice.

There was an "aerator" that came with the pump , basically a plastic pvc end with about 20 little jets, I don't have just the pvc stuck in the tank.  Your idea sounds way better tho.

Edited to fix my stupid quote mistake.

I linked the wrong tubing, what you need is something like this, with pressure-compensating fittings already in it, integrated mesh filters to keep solids from backing up in the works, and a little more heavy-duty hose.

--Dave

EDIT: Doing the math, you're going to need a 3.5 foot length of 6 inch pipe, or a larger diameter (1200 inches around a 6" diameter is 63 turns, or 40 inches of close-wrapped coils.  Or you can cut and cap off the excess length of drip-tube, if that's too big a pipe to be sticking in your septic tank.

dusematic: Solving a complicated problem is a good workout for your mental skills, and you need a *lot* of money before $3K is worth spending just to avoid getting your hands dirty.

[nurtsi]

I don't know what kind of septic tanks you have over there, but my parents had the same problem few years ago.

Since their house was built a while ago, the septic tank is basically a tank with a pipe coming out and travelling some distance beneath the ground (you can't build septic tanks like these anymore here, they tightened the environmental laws since then). Anyhow, the idea is simple, the poo sinks to the bottom of the tank and just water goes into the pipe. The pipe is full of small holes from through which the water gets absorbed into the soil.

The problem is that there is always some light particles in the water that during the years clog the small holes in the pipe. Usually they first clog the holes on the bottom of the pipe and then gradually all the holes higher up. After a while, the excess water doesn't get absorbed to the soil anymore, and the tank starts filling up and eventually overflows.

So the solution for the problem was to change the pipe. That means digging up the old one and putting in new one. We also put some rubble around the new pipe so that the soil isn't directly connected to the pipe. Hopefully this will make it last longer until the next time. From what I understand, you need to change the pipe in these roughly every 10-15 years or so.

[MahrinSkel]

You sound like a guy who just likes to wrench.  Someone who likes tools and gadgetry and tinkering.  That's awesome.  My rant is about unappealing shit that you don't want to do.  Or that seems like a good idea if you're retarded (spending 30 minutes in Home Depot for some nails that you could get at Ace Hardware in two minutes for 50 cents more).  I'm talking about the true underlying costs of being too cheap.

If all I need is a box of screws or nails, and I'm in or near WalMart anyway, I won't sweat the extra pennies.  And if I know that something is beyond my skills or requires tools it isn't worth buying for a one-off job, I'll call in a professional.  And if the hassle factor exceeds the dollar value, I'd rather be playing games than mess with it (like dealing with keeping the yard up well enough to keep the HOA from sending me nasty notes).

But $3K is a big chunk of money for most people, you can buy a functional used car for that, or pay for a semester of state college tuition.  It's worth getting stinky to avoid, if you're sure you understand the problem and how to fix it cheaper.  Installing that ducted fan and insulation in summer heat wasn't *fun*, but it was worth it, where spending the money for a professional wouldn't have been.

--Dave

[Yegolev]

One would think a young man bright enough to figure out a mechanical contraption and the logistics for performing this task wouldn't be so financially insolvent as to have to divest so much time and energy into personally solving the problem, and just shell out the three grand.

I work 60 hours a week, I'm not coming home to do a little research and engineering on the side. There are more leisure options than TV, use your imagination.

I'm sure the answer somehow involves these two quotes.

[Sheepherder]

You sound like a guy who just likes to wrench.  Someone who likes tools and gadgetry and tinkering.  That's awesome.  My rant is about unappealing shit that you don't want to do.  Or that seems like a good idea if you're retarded (spending 30 minutes in Home Depot for some nails that you could get at Ace Hardware in two minutes for 50 cents more).  I'm talking about the true underlying costs of being too cheap.

Dude saved $1800, my guess is you forgot to carry the four zeros.

Also, Baldric's figures way back in 08' on the pressure of water and/or pvc are wrong.

Your pump should need no more than 22.5 psig output to get the air to the bottom of a 15 foot pond.

[Chimpy]

To be honest, this whole "my time is worth more than I would save nanner nanner" stuff all sounds almost like someone is insecure in his ability to keep a hammer from hitting his own thumb to me.

As for the fixing the poop issue, while I commend your ingenuity and desire to fix it yourself, for me working on a septic system is something I would pay someone to do. Carpentry or moderate electrical work I am more than happy to do, but messing with the poop end of plumbing is where I draw the line. Hat's off to you sir.

[NiX]

Split and denned all the "Life Lessons from Duse" shit.

No more.

[Broughden]

I don't know what kind of septic tanks you have over there, but my parents had the same problem few years ago.

Since their house was built a while ago, the septic tank is basically a tank with a pipe coming out and travelling some distance beneath the ground (you can't build septic tanks like these anymore here, they tightened the environmental laws since then). Anyhow, the idea is simple, the poo sinks to the bottom of the tank and just water goes into the pipe. The pipe is full of small holes from through which the water gets absorbed into the soil.

The problem is that there is always some light particles in the water that during the years clog the small holes in the pipe. Usually they first clog the holes on the bottom of the pipe and then gradually all the holes higher up. After a while, the excess water doesn't get absorbed to the soil anymore, and the tank starts filling up and eventually overflows.

So the solution for the problem was to change the pipe. That means digging up the old one and putting in new one. We also put some rubble around the new pipe so that the soil isn't directly connected to the pipe. Hopefully this will make it last longer until the next time. From what I understand, you need to change the pipe in these roughly every 10-15 years or so.

Yes, they were called leech fields. No most places dont allow them anymore. Thankfully they definitely dont allow them when you have a house on the lake anymore.
(It was disgusting in Maine when we would get a heavy rain and poopy water was streaming from the leech field into the lake)