After using potash alum as a coagulant I have the impression that our sand filter is not as efficient as before anymore. Any experiences with that? Backwashing has been done of course.
Can use of potash alum/tawas KAl(SO4)2 mess up filter sand?
- Thread starter sunrise
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Re: Can use of potash alum/tawas KAl(SO4)2 mess up filter sa
Normally alum will backwash out of the filter without any problems, however in some cases it can combine with other things, like suntan lotion, and form a sticky mess that needs to be manually scraped out of the filter. Instructions for using alum normally specify that you shouldn't run the filter until the alum is removed from the pool, in order to avoid this issue.
Normally alum will backwash out of the filter without any problems, however in some cases it can combine with other things, like suntan lotion, and form a sticky mess that needs to be manually scraped out of the filter. Instructions for using alum normally specify that you shouldn't run the filter until the alum is removed from the pool, in order to avoid this issue.
Re: Can use of potash alum/tawas KAl(SO4)2 mess up filter sa
In the meantime I had the filter apart, removed the sand, checking the tubes and laterals for damages, found nothing, the sand is as it should be up to 6 inch below the top of the filter, no sticky sand found, no accumulations of dirt.
The situation is as worse as before: Filtering never get´s the fine particles out even after a 6 or 10 hrs. Adding only a handful of alum get´s the water clear after 2 hours.
Before using the alum the filter worked perfect, however, if the water was cloudy it took sometimes 10 or 12 hrs. to get it clear. Does that mean that now I always have to use alum? It might save electricity, cost here only 0,85 $ per kilo but anyway, I would prefer to go without if if necessary.
Do I have to change the sand or will thorough washing of the sand (out of the filter since backwashing seems not able to do it) and maybe leaving it in the sun for 2-3 days solve the problem?
Any experience with that?
Using the alum to let the fine particles sink down to the floor and then vacuuming it into waste does not work as perfect as catching it in the filter because it will always be stirred up no matter how carefully moving the vacuum.
JasonLion said:
In the meantime I had the filter apart, removed the sand, checking the tubes and laterals for damages, found nothing, the sand is as it should be up to 6 inch below the top of the filter, no sticky sand found, no accumulations of dirt.
The situation is as worse as before: Filtering never get´s the fine particles out even after a 6 or 10 hrs. Adding only a handful of alum get´s the water clear after 2 hours.
Before using the alum the filter worked perfect, however, if the water was cloudy it took sometimes 10 or 12 hrs. to get it clear. Does that mean that now I always have to use alum? It might save electricity, cost here only 0,85 $ per kilo but anyway, I would prefer to go without if if necessary.
Do I have to change the sand or will thorough washing of the sand (out of the filter since backwashing seems not able to do it) and maybe leaving it in the sun for 2-3 days solve the problem?
Any experience with that?
Using the alum to let the fine particles sink down to the floor and then vacuuming it into waste does not work as perfect as catching it in the filter because it will always be stirred up no matter how carefully moving the vacuum.
Re: Can use of potash alum/tawas KAl(SO4)2 mess up filter sa
Water clarity begins and ends with correct water chemistry. The filter will only do it's job well if your chemistry is correct. Can you post a complete set of test results?
Water clarity begins and ends with correct water chemistry. The filter will only do it's job well if your chemistry is correct. Can you post a complete set of test results?
Re: Can use of potash alum/tawas KAl(SO4)2 mess up filter sa
Sorry, not available because these TFT and Taylor kits are not available in the Philippines, only this:Blue Devil B7770 8-way Pro OTO Test Kit for 30 $, (Same as B7448 w/ Cyanuric, Hardness, Base Demand) see here: http://www.thehottublady.com/liquid-test-kits.html. Do you know this, can you recommend this kit? I would like to measure Cyanuric.
But the water chemistry was no problem before. Chlorine is kept at 1,5 with Trichloro granular, ph likes to stay at 6,8 and can be raised with soda ash as calculated with the pool calculator to 7.2, making additionally the water cloudy and will be filtered out again??
Sorry, not available because these TFT and Taylor kits are not available in the Philippines, only this:Blue Devil B7770 8-way Pro OTO Test Kit for 30 $, (Same as B7448 w/ Cyanuric, Hardness, Base Demand) see here: http://www.thehottublady.com/liquid-test-kits.html. Do you know this, can you recommend this kit? I would like to measure Cyanuric.
But the water chemistry was no problem before. Chlorine is kept at 1,5 with Trichloro granular, ph likes to stay at 6,8 and can be raised with soda ash as calculated with the pool calculator to 7.2, making additionally the water cloudy and will be filtered out again??
Re: Can use of potash alum/tawas KAl(SO4)2 mess up filter sa
I am guessing here, but since you are a trichlor user, your cya level is likely high. Many many posters have come on saying just like you:
No good details on the kit on that webpage, but hopefully the cya test is a liquid one...which is good.sunrise said:
I am guessing here, but since you are a trichlor user, your cya level is likely high. Many many posters have come on saying just like you:
and it turns out the pool finally went over the edge of having too much cya and not enough FC in the pool.sunrise said:
Re: Can use of potash alum/tawas KAl(SO4)2 mess up filter sa
Yes I know about that CYA problem and am trying to find out the amounts of test liquid but the "ask a question" button does not work on that website, maybe to keep stupid questions away....
But before I have that kit, let´s assume that it´s correct, also because we just filled the pool again 3 weeks ago, had a leak, with rainwater btw. How about the behaviour of the soda ash, is that normal to make the water cloudy and will be filtered out again?
And the sand, can it be messed up by alum?
Yes I know about that CYA problem and am trying to find out the amounts of test liquid but the "ask a question" button does not work on that website, maybe to keep stupid questions away....
But before I have that kit, let´s assume that it´s correct, also because we just filled the pool again 3 weeks ago, had a leak, with rainwater btw. How about the behaviour of the soda ash, is that normal to make the water cloudy and will be filtered out again?
And the sand, can it be messed up by alum?
Re: Can use of potash alum/tawas KAl(SO4)2 mess up filter sa
Now I got this from my Alum supplier in Manila:
"Hello Mr. B.,
Regarding the tawas (local name for alum) used by other clients, mostly have DE filter, and when they use the tawas, their filter elements became brittle. Tawas is quite harsh and it literally eats up materials even marbles, so it could be that the tawas ate up some of the silica sand therefore making the sand irregular in shape, that’s why it is not filtering properly."
Can somebody here verify that? If that is true, nobody should use it anymore and I have to replace our filter sand.
Now I got this from my Alum supplier in Manila:
"Hello Mr. B.,
Regarding the tawas (local name for alum) used by other clients, mostly have DE filter, and when they use the tawas, their filter elements became brittle. Tawas is quite harsh and it literally eats up materials even marbles, so it could be that the tawas ate up some of the silica sand therefore making the sand irregular in shape, that’s why it is not filtering properly."
Can somebody here verify that? If that is true, nobody should use it anymore and I have to replace our filter sand.
Re: Can use of potash alum/tawas KAl(SO4)2 mess up filter sa
I thought the thing that caught the dirt in the sand was the fact that the grains were "irregular"? Now if somehow this nasty stuff end up smoothing the sand, then that could be a problem.
If you just replaced all the water, then your CYA may not be very high yet.
I thought the thing that caught the dirt in the sand was the fact that the grains were "irregular"? Now if somehow this nasty stuff end up smoothing the sand, then that could be a problem.
If you just replaced all the water, then your CYA may not be very high yet.
Re: Can use of potash alum/tawas KAl(SO4)2 mess up filter sa
That is also what I thought, becoming round instead of irregular. So I will replace the sand and post here if that solved the problem. Before doing that, will test for CYA level with that new kit coming with the sand.
Any recommendations for a replacment for Alum, another coagulant? If possible several brand names so I can look around here if they carry that.
That is also what I thought, becoming round instead of irregular. So I will replace the sand and post here if that solved the problem. Before doing that, will test for CYA level with that new kit coming with the sand.
Any recommendations for a replacment for Alum, another coagulant? If possible several brand names so I can look around here if they carry that.
Re: Can use of potash alum/tawas KAl(SO4)2 mess up filter sa
We do not typically recommend or need to use any products like that. Maintaining the chemistry and the use of the filters keep the pools clean.
Inspect the internals of the filter and verify something is not damaged that could be letting the dirt through.
We do not typically recommend or need to use any products like that. Maintaining the chemistry and the use of the filters keep the pools clean.
Inspect the internals of the filter and verify something is not damaged that could be letting the dirt through.
Re: Can use of potash alum/tawas KAl(SO4)2 mess up filter sa
A few months ago when I had all the sand out I did already inspect all filter and valve parts including the laterals, all OK. Before using the Alum the filter worked perfect so it must have been the use of the Alum. I will post if changing the sand fixed the problem.
A few months ago when I had all the sand out I did already inspect all filter and valve parts including the laterals, all OK. Before using the Alum the filter worked perfect so it must have been the use of the Alum. I will post if changing the sand fixed the problem.
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