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Reducing TDS with out chemical - an experiment that worked.

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We have had Poly Pads for a little while and I used it when I set my tank at home and was pretty impressed with the results.

Then I had a thought - if the Poly Pad was soo fine (40 Parts Per Billion Filtration) and it took out fine particles and also collected copper, alluminium, iron and ammonia then it would also reduce the TDS of water.

We first tried it by rolling it and cutting a 600ml drink bottle base of the drink container an putting in the poly pad rolled to fit in it.

The first lot of water out of the tap was off hand had a TDS of 800 and pouring the water through the drink bottle 8 times reduced the TDS by about 200 - [MENTION=7848]PETFISH[/MENTION] will have a better memory of the start and the finish TDS

Now clever Petfish said - "I did not think you were going to do it that way I thought you were going to put it in a filter and let it run" yep I missed the simple approach.

So we tried it again and the next lot of water that came out of the same tap had a TDS of 189 and Petfish and I looked at each other then realised that the initial water picked up more from the tap the first time from lines more than the second.

Anyway we left the filter with the poly pad in it for two days and it went from 189 to I think 150 again [MENTION=7848]PETFISH[/MENTION] will have a better memory on the exact drop.

If you are looking at a way to reduce your TDS there is an option without going to the cost of a RO unit.

Anyway this is the stuff we used to get the results if you are interested in lowering your TDS.

Poly Filter 20cm X 10cm (8 in X 4 in)

PF4080-2.jpg

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Wow, i love when an experiment works. Do you think given enough time it could reduce tds to zero? If so this would work well in in ageing barrel with a heater, lower the Tds to zero, remove filter, add shrimp mineral, Malawi salts or whatever is needed for the particular tank your water changing, then add the perfect water for the least stressful waterchanges a fish could ever get.

Great find and thanks for sharing.

Cheers mick

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Quick question. Do you need to cover the surface area of the filter? For example a 2215, Will I need one to match the size of the filter pads? Or could I just use a portion and it will just absorb it?

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Interesting....I'm willing to give it a go

However the data on the product says "Will not soften water or remove trace elements in solution"

Might be interesting to test Gh and Kh?

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Quick question. Do you need to cover the surface area of the filter? For example a 2215, Will I need one to match the size of the filter pads? Or could I just use a portion and it will just absorb it?

you would be best to get the 30 x30 pad and cut to fit snug in your filter, being so fine the water would channel around the pad if not cut to fit snug around edges.

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Interesting....I'm willing to give it a go

However the data on the product says "Will not soften water or remove trace elements in solution"

Might be interesting to test Gh and Kh?

i will do this today and let you know.

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Wow, i love when an experiment works. Do you think given enough time it could reduce tds to zero? If so this would work well in in ageing barrel with a heater, lower the Tds to zero, remove filter, add shrimp mineral, Malawi salts or whatever is needed for the particular tank your water changing, then add the perfect water for the least stressful waterchanges a fish could ever get.

Great find and thanks for sharing.

Cheers mick

Hi Mick,

It wont reduce TDS to zero as it only remove's the heavy/bad mineral's not the good one's, however it does lower the TDS to a suitable level for crystal's etc, for african's for example you would need to add salts and buffers/kh generator,as usual

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Any idea on how long they last? When you do a water change later will it also remove the tds back to that level again?

Interested to know if it can be re-used /regenerated (just by rinsing) or it's a disposable product. If disposable, is there a period/sign to tell that it's effectiveness has declined - likely dirty/cloudy water? What volume of water can a single pad do?

This will be perfect for my top filter project.

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Interesting....I'm willing to give it a go

However the data on the product says "Will not soften water or remove trace elements in solution"

Might be interesting to test Gh and Kh?

That is one thing that we did not test on it but worth a test all the same.

We were experimenting with the idea of working on straight tap water.

This means the results will differ from location to location and a final TDS will also differ from location to location.

Although you can put it in your canister while filtrating your tank and this would reduce the life of the product as I would expect it to draw more out but do a very good job all the same and this again will depend on the amount that it draws from the water.

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Interested to know if it can be re-used /regenerated (just by rinsing) or it's a disposable product. If disposable, is there a period/sign to tell that it's effectiveness has declined - likely dirty/cloudy water? What volume of water can a single pad do?

This will be perfect for my top filter project.

It can be cleaned to a certain extent but you would notice the deterioration of the results to a point where you would replace it or it turning black. It is also handy to get an indication of just what is in your water with the changing colour when it is removing different properties.

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By TDS do you mean electrical conductivity rather than TDS?

Tds and ec are two ways of testing the same thing and can be converted to each other depending on which tester you have.

Cheers mick

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Tds and ec are two ways of testing the same thing and can be converted to each other depending on which tester you have.

Cheers mick

Not quite. TDS measured all dissolved solids (hence "total dissolved solids") vs EC measuring only those ions which are conductive. The two are pretty closely linked and there are "rules of thumb" out there to guess one based on the other, but its only a guess. Relying on conductivity measurement to try to ascertain TDS is always going to be erroneous.

I'm really only just beginning to wrap my head around all of this as I school up in preparation for a discus experiment so I'm no expert, but I think it would be interesting to know a little more about what the product is actually doing, especially as the product description states that it does not affect hardness. As John pointed out this product removes heavy metals, but is that all it removes? If that is the case then I would question whether or not this product has any real value. If it is also removing sodium ions then perhaps if used in concert with something like Macropore Gold (which lowers GH whilst having no real net effect on TDS) it might provide a more compelling use case.

Of course I am thinking of things in relation to my own project. For other applications things might be a little different but it is hard to know as I don't think anyone is truly all over it when it comes to GH/KH/TDS/EC and which of these is the primary concern when it comes to catering or a specific species.

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So I've done a little more light research on this product and it seems it has no effect on sodium, calcium or magnesium. It is reducing conductivity simply by removing iron and copper. While that has a measurable effect on the us/cm reading, I am doubting that it actually has any meaningful impact. Its almost like cheating on a test - it removes those metals to lower the result, but we are typically looking for a low EC reading as an indicator of low TDS, which isn't being affected in the way that we would want it to be (by lowering the amount of sodium.)

The product still excels are removing phosphate, ammonia and nitrate (and effectively reduces nitrates by minimising the amount of ammonia to be converted) as well as providing very fine mechanical filtration, so it is not without purpose, but as a potential substitute to RO it falls short of the mark.

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So I've done a little more light research on this product and it seems it has no effect on sodium, calcium or magnesium. It is reducing conductivity simply by removing iron and copper. While that has a measurable effect on the us/cm reading, I am doubting that it actually has any meaningful impact. Its almost like cheating on a test - it removes those metals to lower the result, but we are typically looking for a low EC reading as an indicator of low TDS, which isn't being affected in the way that we would want it to be (by lowering the amount of sodium.)

The product still excels are removing phosphate, ammonia and nitrate (and effectively reduces nitrates by minimising the amount of ammonia to be converted) as well as providing very fine mechanical filtration, so it is not without purpose, but as a potential substitute to RO it falls short of the mark.

That is pretty much spot on as it will remove particles from the water but not to the extent of a RO unit which will strip the water. It will improve the water but not totally strip the water to the extent of RO. It is better than you currently have water wise but not as good as RO.

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Personally I think the most compelling use case for this product would be as the final stage of mechanical filtration in a sump (on any system, be it Africans, Americans, tropical or even marine). In the past I have seen people use a layer of felt as an ultra fine mech filtration, but this would have the added benefit of the chemical filtration as well. I might give some a go in the future if I can devise a method to apply it inline and under pressure.

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