How much sand Do I have? *Updated* with sand in glass viewer and lack of leverage in MPV handle problems. RESOLVED!

[Desiato]

Ok, not your regular question I'm sure. A long story short, I'm helping a friend, who's sand filter has a broken return connector, so I've had to remove the sand. Despite it saying in large friendly letters on the side "100kg of sand & 50kg of gravel" (we're in Spain), there was no gravel to be seen. I've checked with the manufacturer and they are still sticking with this ratio so who am I to argue? (I read others here have a 80/20 sand/gravel split). My problem is, I don't know how much sand I have and it is sitting in a bin and a bucket soaking wet. Two things crossed my mind, one is to ask you guys if any of you have emptied your sand filters into bins and can judge just from looking at mine how much I'm likely to have? You can see that the large bin is almost to the top but the rubber one to the right is about half full. Yes, I know, bit of a dumb question but I thought it was worth a short, a more sensible question is to ask how far from the top of the sand filter should the sand be? I'll add the 50kg of gravel and then add the sand and stop if and when it gets xxxx distance from the top. Any replies, sensible or not, welcome.

The sand filter in question just happens to be the same as mine but with a different name on it Catalogue of pools spare parts | Fluidra



I should add the reason it is sitting in bins and buckets of water is because I've been cleaning it. Hadn't finished with the smaller bucket when I took the video/photo.

 

[GregN]

I think you are on the right track. You can weigh the rocks and get an accurate measurement so that is straigt forward. I would assume the mfg recommendation of 100 kg of sand is on a dry weight basis, and this would be difficult for you to weigh because the weight of your buckets is attributed to sand plus water. You could go to the trouble of laying the sand out on a tarp set over a sloped surface, and the water will gravity drain from the sand to a point, and you could help that along by turning it over to help it dry, but that's quite a bit work and probably unnecessary.

I would probably just put the correct volume of stone in based on weight, and then start putting in your existing sand and I would think as long as you don't go higher than 2/3rds of the way up from the bottom of the filter you should be OK, but that's a guess on my part as that's about the height of just sand in my Hayward filter. Can you contact the mfg. and ask your question about height of sand as opposed to weight? If the filter was working properly initiailly, maybe you peer in the top of the filter and see if there is a "ring" along the wall of the filter which would represent the level of sand prior to removal.


Good Luck,
Greg

 

[Desiato]

Thanks for the reply Greg. The gravel is the easy bit as I need 50kg and I've got 2 x 25kg bags on the way. It did cross my mind to try and lay the sand out on a tarp to let it dry but as neither myself or my friend has one, I'm probably going to go with the guesswork approach. I can't even use my own filter for comparison (which just so happens to be the exact same sand filter) as it has glass media in it and if memory serves, the manufacturer told me not to use gravel but to use an extra bag of glass media...or something like that, it was quite a few years ago now. Unfortunately I've taken the sand filter out onto the lawn and hosed it down so I'm guessing there may not be much left of a water line ring but I'll have a good look tomorrow as I'm still waiting on some replacement parts before putting it all back together.

 

[Desiato]

*An update*

I probably should start a new thread but one of the possibilities is that I have too much sand in the filter so I've decided to continue this thread.

So I replaced a couple of bent laterals, the broken collector connector (that connects the lateral L shaped arm to the sand filter) and re-glued the air tube to the base of the lower lateral collector (and secured it a few inches up from the base with half a peg (as a spacer from the central pipe) and a stainless steel hose clamp. Just as well I did as I had to bend the air pipe to get the L shaped collector into the sand filter, I'm sure it would have snapped off again with out this extra support).

I tried to work out where 2/3 full would be on the filter and after a few measures inside and out I decided that 2" above the top inlet pipe (on the side of the filter) would be roughly 2/3rds. I added the two bags of gravel (3 to 5mm, label and manufacturer said 6mm but I couldn't find any 6mm, surely this can't be the issue? It only had sand before so any gravel is better than no gravel, no?), I cut a small corner in the bag and slowly poured it into the filter that I had half filled with water. I felt around the laterals after the first bag, it hadn't covered them so I pushed the gravel around a bit and the laterals I felt were still attached but I'll be honest, I didn't check them all sooo, maybe I missed one?

After adding back the old sand and closing everything up, I did a backwash and everything seemed fine. I then did a rinse and noticed that the glass viewer was full of sand. I remembered this happens with new sand so thought it might be because of the new gravel so repeated the process. Do a backwash and the sand disappears from the glass viewer, rinse and it is full of sand again. I did this 5 more times hoping it would clear up and even left the rinse going for 5 minutes a but the glass viewer still had sand swishing around it. To describe the rinse in more detail, the sand rushes in at the start of the rinse, swirls for a minute or so and then starts to thin out so what does this mean? If the sand in the glass is thinning out does that mean it's no longer pulling sand from the filter so does that rule out a broken lateral? I would have thought that if there was a broken lateral it would have continued to pull sand from the filter until it ran out of sand?

Now just when you were sitting there saying "it HAS to be a broken lateral", let me throw this into the mix. When I went to inspect the damage after the bracket broke and the flood gates opened, I also saw some sand in the glass viewer. I decided to open up the MPV and saw that the gasket (that comes fixed to the MPV manifold) was shot to bits. I ordered a new one and whilst I was waiting for the parts to fix the filter, replaced it. I struggled to find the gasket thing but eventually found a supplier in France and paid the high postage. Unfortunately the supplier forget to send the 2 washers so rather than wait any longer I reused the old ones. I sprayed some silicone lubricant on them (as seen on youtube) and the hole that the centre part fits into and it all seemed fine. The only thing is, when I put it all back together I noticed I didn't have as much leverage as I used to. After todays problems with the sand in the glass viewer, I took the MPV apart, sprayed some more silicone lubricant on the O rings and hole the rings go through and pushed them together. I noticed that the spring didn't push the two parts apart as much as it should have, seeming to stick on the upper O ring. This was working the day before, why is it sticking now?

Here's my problem though, I sit the new gasket head piece into the MPV (which is full of water, don't remember mine being like that, relevant?) with the open triangle at the top. I then place the washer, spring and washer onto the central column and then push the main MPV top plate down onto the new gasket central column. With one hand pushing down on the MPV top plate to depress the spring, I use the other to put the the 8 screws in the top plate and loosely fit the nuts below. I slowly tighten them with a screwdriver above and a small spanner holding the nuts below, crossing from one side to the other to distribute the pressure down on the spring. When it's fully tightened, I then grab the handle, drop it into position and find that I can easily slide the pin in from the right hand side. Now this shouldn't be this easy, when I first did this on my own, I had to hit the pin quite hard with a hammer and screwdriver to get it to slowly pop out the side. Because the pin goes in quite easily there isn't much in the way of leverage. I've got decent leverage on my own MPV but not on this identical one and the only difference is one has new washers and the other doesn't. Can washers make that much of a difference? They look absolutely fine so what is causing the lack of leverage?

Now I've been racking my brains trying to work this out but I can't get passed this bit. When I put the new gasket piece into the MPV it is sitting on the base over the holes that lead to all the pipes, it can't go any lower. When I place the washer/spring/washer on top and push the head piece of the MPV down onto the gasket piece, I am lowering the top MPV piece down onto the gasket piece and compressing the spring. Again, the gasket piece can't go any lower. So when I put the handle on, where has my lack of leverage gone to? Logic says that the gasket piece must have risen up into the MPV top piece and there is now a gap between the rubber gasket and the hard base where the holes to the pipes are. Now that I write this, I suppose as I'm wiggling the top piece down the rubber gasket piece could be rising up? Oh God!

More info, Just to see if the sand would return to the pool I turned the MPV to filter and started the engine. Straight away I could hear the sand bashing its way down the pipes to get to the pool so immediately turned off the motor. So rinse and filter are sucking sand from the filter but is it the gasket thing sticking open, an unlikely broken lateral or too much sand in the filter? (as I didn't know how much I had and may have over filled it). I'm beginning to think it could be the washers causing the gasket thing to stick open but quite how the sand gets through a perfectly working lateral to get the the MPV gasket thing, I've no idea.

Sorry for it being so long but I tend to think that more info is better than too little but I appreciate it can also put people off from reading it at all.

 

[Desiato]

Oh well, I guess I'm talking to myself but if anyone has stumbled in here by accident, here's something to make you laugh. I discounted the possibility of it being a diverter fault by switching mine with my friends and the same thing happened, glass viewer full of sand. Emptied the filter, had a good feel around the laterals, all seem to be in order...let me just reach round the back where I can't see the last lateral...err...where is it? Yep, I had managed to fit 7 laterals and left the 8th sitting on my workbench (long story about trying to find the right size because the supplier changed the size but didn't update their website and I kept being sent the wrong size). About two thirds of the sand have been rinsed down the drain so I bought 4 new bags of sand, rinsed the gravel through a sieve to get rid of the old dirty sand and all is well again.

I added an extra washer below the handle to give it some extra leverage and it helped, not perfect but better. All working now, just need to SLAM to get it looking marvellous again.