Sand filter extremely "clogged" after 4 months

[Magicwiz2]

I have a service company, and rarely do I run into problems that I can not figure out.

I have a new client that runs a horse rehabilitation and conditioning center. They have a 2000 - 3500gal for lack of a better word trough that has a treadmill in it for the horses to run on. Since this was installed it has never been clear. I am determined to make everything work right and clear the water up.

There are 3 Martin 100 series 2hp motors that each have a Pentair Triton II Tr140's attached to them. The problem that I have run into is that they tell me they are changing the sand every 6 months or so. I took the top off one of the filters the other day and was suppries to see that the 4 month old sand is all clumped together. At first when I saw it I thought it was related to a hydraulic line that busted and dumped about 3 galling if oil into the pool from the treadmill but when I showed it to them they they informed me that it looked and smelled just like the same stuff that they clean off the bottom from underneath the treadmill every 2 weeks or so. In the 12 years I have been in this business I have never seen a sand filter this bad even with the over use of clarifies. They told me they don't really use clarifies they just use a blue dye to make the water look "better" and give it a blue tint instead of the cloudy grey color that it usually is.


When the horses get in this treadmill they do usually mess in it at least once and a lot if times more than that, and as with human waste it most of the time sinks but sometimes float.

They were using cal hypo as their sanitizer which with our high alkaline and oh water makes it cloudy enough without all this other waste in the pool. I am trying to get the to switch to di-chlor since cya will not be a problem with as much splash out, backwashing, and drain and fills as they do just to keep the bottom clean, but with di-chlor being twice the price it is difficult to get them to change over.

Ultimately I would like to get the water at least a little clearer if not totally clear if possible and to a point where they won't have to change the sand every 4 to 6 months

I have spoken with the folks that manufacture and install these and they tell me that there are facilities that use there treadmills without as much trouble as they are having.

If anyone has any suggestions or ideas I am all ears. I am even willing to spend a little money if it means we can get better water clarity and develop a routine for them to use to achieve those results.

 

[Patrick_B]

Welcome to the forum Magicwiz !

Man, you know how to walk on with a tough one. This is certainly beyond the norm of what we deal with here, but it's interesting to think about what might be done to help. Please don't have your hopes up that you'll find the answer you need here, but there is no harm in discussing it. So, they changed the sand after they cleaned up the hydraulic leak? I would surely think it would be difficult to get it all and any residual would contribute to the clumping. How much volume of water are we talking, and are the filters staged or all just filtering on their own? That is a lot of filtration, but I imagine you need all you can get in that situation. Have you looked into what similar setups look like in comparison to this one? That is something I would surely want to know for a starting point, because this is a very unusual demand on a typical pool filtration setup even if it is multiplied. As for Chlorine sources, that is another huge ball of wax in this scenario because of the extreme demands that will be placed on it. I'll leave it here for now, but will check back when you answer. Sorry not to be of more help, but again, this is really way out of the scope of what we do here. I'm in the water treatment industry myself, but there are very specialized systems and treatment processes for such extreme situations.

 

[Magicwiz2]

First I would like to tank you for the response and willing to discuss this.
Second I realize that I may and probably won't find the easy fix. But ideas and suggestions are all I am after.
Alright now to star answering some of your questions.

Yes the sand was changed after the oil leak. And before that about once every 4 to 6 months.
The treadmill is usually pulled out every 2 weeks and the pool power washed and cleaned out. What I found in the one sand filter is typical for what is found on the bottom of the pool every time they pull the treadmill and clean under it.

The pool is about 3500 gal and that is a Generous estimate as I don't have the exact dimensions or the inclines going into and out of the pool. I am estimating that the pumps and filters are Pumps are turning the water at least 3.5 time an hour.

The filters are all filtering on their own and not staged.

As far other setups go. Based on what I have learned from the manufacturer of the treadmill this is what is typically done and how they are designed. I have not personally seen any of the other setups, but they are the only ones who design the system and it should be the same all around. That being said this facility did get a local builder to install it who did not follow any if the plans ( how he usually did things, and the reason he is no longer in the business) so I wast not completely torn out bit a lot of it was and done.

Also I might mention that there is a guy who works at another one of the businesses this guy owns who does a lot of their fixing of stuff. I asked if his name was "Jerry" and surprisingly it was not. So there is a lot of stuff that is definitely not fixed right. Just one example, on the inlet on 2 of the pumps, I found a lot if thread sealant under electrical tape to keep the pump from drawing in air. It may have "worked". At the time but was far from being a permanent fix. I kinda chucked and shook my head. I was then told by the lady who now runs the place that she was surprised to see the electrical tape as they usually use duct tape to fix and hold things together. I don't think she was kidding.

I realize this is more of a do it yourself forum and really appreciate you taking the time to discuss this with me.

 

[Patrick_B]

No problem, I am just kind of stumped on what to do. I cannot imagine why they were changing sand so often and what benefit they thought it would bring. The problem is load on the system and new sand won't do anything for that. The thing that I keep thinking is that there has to be a way to remove the heavy solids load as soon as possible. With the current setup, I guess back washing is the only way, but it must be done. The amount of chlorine it will take to overcome that kind of load will just be unreasonable. Trichlor as you say would be exorbitant in terms of cost and for FC purposes it is no more effective than bleach.

 

[Magicwiz2]

Before I showed up. They were just putting cal-hypo in. I asked how much a day and the response I got was 3-4 scoops. I then asked what the chlorine lvls were free vs combined and so on. The response I got was "I don't know, I have a test kit but don't use it, I was just told to put 3 to 4 scoops in". Well fc was <.5 and tc was 7 or 8. Similar situation as far as ph goes. This has been remedied and the water tested at least twice a day most time more. Now granted this was the afternoon and she had been working horses all day so who knows what it was like in the morning by typically they shock at night after the horses are thru being worked.

 

[Smykowski]

Really interesting situation you've got. I'll qualify it like Brushpup did, I have no idea how this is going to work, but we can certainly try to extrapolate the residential swimming pool practices to this situation.

First, I'm not sure any pool filter is designed to handle the kind of load that's going to be put on it, so there's definitely going to have to be manual debris removal. Any large, visible solids need to be removed immediately, and the filter will clear what it's designed to clear - the smaller dirt and other particulates.

Second, urine/urea puts a huge, huge demand on the chlorine in any pool. Ammonia in general takes a ton of FC to oxidize, meaning any time a horse pees in the tank (and I imagine that volume is really, really high), it's going to take a lot of chlorine to oxidize it out of there.

Assuming the large solids are removed and the FC/CYA ratio is maintained (more on this later), I see no reason why the sand would get as gross as you say it is. I suspect that the biggest culprit was the hydraulic leak.

Because of the huge demand that's being placed on the FC in the water, I would guess that our FC/CYA ratio will not work. The FC will just be depleted too quickly. You would probably need to keep it around double what the chart says. For example, for a CYA of 30, use FC of 8 or 9 instead of 4. That may not be enough, and some type of stenner pump or other automation system to continuously add FC to the water might be needed.

 

[chem geek]

The fundamental problem is that there is so much organic load that the chlorine level is not able to be maintained. This results in biofilms in the sand filter and that makes the sand clump together. It is also possible that the organics themselves are leading to the clumping if they are "sticky".

Though you could try and have them maintain the chlorine level which means using a lot more chlorine, I think in this situation you would be better off using supplemental oxidation of some sort even though that would be more expensive. Supplemental oxidation would include non-chlorine shock (MPS) or an ozone system (I don't think UV would be effective enough given the load). They also probably need to backwash the filter more frequently to remove the organic matter that builds up there. There are also specific products to help prevent biofilms and normally these are not necessary if proper chlorine levels are maintained, but you can look at them as insurance -- one such product is Aquafinesse tablets.

If you want to deal with this using chlorine alone, then given their lack of attention for testing and dosing and given the high load, having a chlorine dosing system such as a saltwater chlorine generator or a peristaltic pump (high capacity feeder) would be better and would also work better with automation such as an ORP or FC sensor. This is all a lot more cost, but unless they are willing to stay on top of dosing and testing, there's not much else you can do.

 

[Magicwiz2]

I really do believe that if I can show them a better way to take care of this thing they will be more prone to testing the water more regularly and ever at certain intervals thru the day. The 2 people running the operation seem a lot more willing that the last guy was to do what they need to to make it work. When this thing is operating and looking like it should this will be their money maker and they realize that..

I don't think that a swg will be feasible because of the constant addition of fresh water, who knows it may be. Fortunately this will be the only pool that I take care of that I won't have to worry about the CYA. I really don't think that I will be able to get the lvls up with as much back washing and splash out as there is and this pool being so small.

Of course I would like for them to be able to maintain it with just chlorine. If this can even be achieved for a short period of time and make the water look good, and then show them what happens when they neglect it for probably even a day or 1/2day I might be able to get them to install some type of pump or ORP or FC sensor just as a back up, because inevitably this pool will get neglected at one time or another for whatever reason.

As far as removing the solids as quickly as possible. There is a net on a pole that is within reach if the person working the horse is paying attention.

I don't know about the urine if they do that while running or just when they are standing still. I can't think if a time when I have seen a horse pee while walking I have just seen them poo, but then again I wasn't watching for it either. Defiantly going on my list of questions to ask the operators

 

[Bama Rambler]

I would look at adding a centrifugal cyclone to the suction side of the pump to remove some of the organic load from the filter. I also believe that using chlorine gas or liquid injection is the best way to maintain the system.

How often are they backwashing the filter?
Is there a jet directing water under the treadmill? If not it may help to add one to help sweep some of the debris out of the unit.

 

[Magicwiz2]

They are back washing at most 3 times a day but not by any set schedule. No there is not a jet that shoots water under the treadmill. I will have to look into how much trouble it may be to get one rigged to shoot that way. I have done a little research on the chlorine gas part but have not found much on it. It looks like I am going to try and get some sort of liquid injection set up depending on the cost

 

[Leebo]

What does the manufacture suggest for chemistry and equipment?? To me I would wonder if maybe they would be able to suggest proper equipment for this product.

 

[Magicwiz2]

They did not tell me much in the way of chemistry but all the equipment was part of the package that they put together. This week sometime I am probably going to call them again and try to get them to give me the name of another facility that runs more horses thru their setup and try and talk to someone there that does the maintenance on it.

 

[Bama Rambler]

3 times a day backwashing sounds like a lot unless they're running a lot of horses thru it.
Do you know how many horses they run a day?
Do you know how long they backwash each time?
Sounds like they're not backwashing long enough each time.
Are they running the filter system continously or just when they're running horses in it?

 

[Magicwiz2]

On average they send about 10 horses a day, they backwash till the water gets below the skimmers around 10 min on each one and the filters run 24/7. One of the things I am going to do this next week is install clear sights in the backwash lines to make sure the water is clean when done back washing. And on average each horse poo's I there twice sometimes only once tho

 

[Patrick_B]

I remember seeing the Cyclone unit on youtube this summer and thinking what a good idea it was. I had completely forgotten about that. Excellent suggestion Bama. This system really needs something extra.

 

[Bama Rambler]

Sounds like they need some horsey diapers too.

 

[Patrick_B]

Just checking in for an update. I haven't thought of anything to add unfortunately. Hope something is figured out to help at least a little.

 

[toofast]

Sounds like they need some horsey diapers too.

So I know this was meant to be a joke, but it might be a great idea.

Not diapers per say, but growing up we had horses, and often we would pull carriages with them. My grandfather had a "harness" of some sort then went over the horses rump and had a "bag" that caught most of the poo...I've also seen this on horses in NYC streets, the ones that cart the white carriages around.

ALSO - someone mentioned a centrifugal pre-filter...I have one and it certainly spins out the solids before they enter the filter...plus you can backwash that sucker fast and with little water.

 

[danjaymor]

I am with Bama on this one as well. My first thought was that you've definitely got to "pre-filter" in order to get a lot of the larger chunks and debris out before passing back through the pump and sand filter.

A "spin" or vortex filter is an excellent way to accomodate this. (google "irrigation sand separators" for some looks at some different manufacturers of these)

Maintenance of this unit for this application is very easy as there is no cartridge or screen to plug, and the debris can be flushed out of the lower drain port by using a ball valve and discharge hose to the waste area of your choice.

This would definitely take care of some the "heavy lifting" and take a good deal of load off of your sand filter, just let it take care of the "fines".....

 

[East_Akl_Neil]

Im no expert, but something that should be mentioned, and you may have already done it, but have you tested the fresh water going into the pool?
Also next time your talking to the manafacturers, see if they can send through a recommended plumbing diagram to see how the setup your dealing with compares. As you did mention a couple of people have been involven in the past. It may pay to go back to basics before making too many changes.