home made water purifier

gollum456

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i have been looking at a HMA filter such as this:- http://cgi.ebay.co.uk/HMA-CBR2-METAL-RE ... plies_Fish.

when i asked for information on this at practicalfishkeeping.co.uk i was pointed in the direction of this:- http://www.evolutionaqua.com/acatalog/D ... ators.html.

now, going for the smallest one (12 inch) it says it is good for up to 150000L, so by my calculations will last 19 years with 150L a week water changes.

so here are my two questions:-

1)surely this is too good to be true as i thought activated carbon when used in a filter became "useless" within 4-5 days, so wouldn't the same roughly apply here?

2)isn't this just a tube with high grade activated carbon in it? these are £65 to buy. wouldn't a DIY job be quite easy? like building a co2 reactor for example, thats all it looks like to me.

any thoughts welcome
 

Garuf

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I don't think there's anyone on here who actually uses one so no doubt the knowledge base is somewhat limited. I've been tempted by a HMA myself as I have exceptionally high levels of heavy metals back in stoke rendering inverts impossible but it's easier to just not have shrimps than fighting water content and parameters.
 

Lisa_Perry75

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Perhaps you could mention why you want a water purifier? You might find that many people on this forum do not think them necessary, so you may end up not needing one at all. Saving you hassle and money!
 

gollum456

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Lisa_Perry75 said:
Perhaps you could mention why you want a water purifier? You might find that many people on this forum do not think them necessary, so you may end up not needing one at all. Saving you hassle and money!

actually its about less hassle. i like to fill directly to the tank and i guess i dont have full confidence that adding seachem as i'm filling the tank is neutralising everything. having said that fish seem fine.

and just to remind you, its this i'm looking at, http://www.evolutionaqua.com/acatalog/D ... ators.html

this is different to an ordinary hma filter and can quickly be connected and disconnected to my mixer tap!
 

ceg4048

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Hi,
There is a huge difference between a simple activated carbon filter and a heavy metal axe type filter. Carbon doesn't do a good job at all of removing heavy metals such as lead, iron, copper, chrome, mercury, zinc and so forth. In order to accomplish that you need special resins that work via ion exchange. A true HMA therefore will have either a multi-stage construction, where each stage does a particular job. Heavy metals or other debris may be present in particulate form as well as dissolved ionic form, so you'll typically have a mechanical removal as the first stage. Since the carbon will be good at removing the chlorine/chloramine (which might also damage the resin) then this will be the second stage. It is in the subsequent stages where the special resins will perform the metal removal. There are some single stage filters such as the ones used in household drinking water filters, but these combine the resin impregnated on a fine mesh + powdered carbon matrix. The single stage then does all three jobs but probably is less effective than the multi-stage units.

If you are just using a carbon block therefore then this is just basically a mechanical dechlorinator, not a HMA. For optimum chlorine removal the flow rate through the block needs to be very slow because carbon does not absorb the chlorine. It does not work by any chemical reactions but by simple adsorption via Van der Waals forces, which is just a simple electrostatic force between dipole molecules of the contaminant with the carbon molecules.

To me using carbon block for dechlorination is a LOT more hassle, because the flow rate has to be so slow that you may as well prepare the new water hours or days in advance. Compare this to just adding a few drops of dechlorinator, which works quickly and continuously to neutralize the chlorine and to neutralize the ammonia released by the breakup of chloramine. If you add a little too much to the water it's no big deal as it's non-toxic and whatever excess remains will work to your advantage by neutralizing any stray ammonia (NH3). The only time the carbon block makes sense is if you are performing an automated and/or unattended water change, otherwise it's no contest. The active ingredient is typically Sodium HydroxyMethaneSulfonate.

Cheers,
 

dw1305

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Hi all,
It is just like Clive says, a true HMA filter would be a mechanical filter followed by an activated carbon block and a multi-stage cation exchange resin column. We've used them in the lab., but I can't remember quite what for, the ones we used were "Chelex" & "Amberlite XAD" ion exchange resin columns. I don't know the cost of them, but I remember they were very high maintenance.

I've had a look at a hobbiest type 3 stage carbon block HMA filter and it looked very good value, the "pod" contained "Purolite C107E" which is "a high purity, high capacity polyacrylic weak-acid cation exchanger developed to treat water for potable use", from http://www.osmotics.co.uk/.

cheers Darrel
 

gollum456

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clive,

so you are saying that its ok to add water and dechlor directly to tank? as i said my fish dont SEEM to mind.
 

Dan Crawford

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gollum456 said:
so you are saying that its ok to add water and dechlor directly to tank? as i said my fish dont SEEM to mind.
Yes it's fine IMO
I never dechloronate and ive never lost a fish due to it. My fish deaths are always CO2 related :oops:
 

ceg4048

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Yeah, as Dan the Man said, just add the dechlor exactly as you're doing now. This has been standard operating procedure for years. Why would you want to make your life any more complicated than it already is? Just add a few drops and get on with it. Dechlorination ought to be among the least of your worries.

As Dan mentioned, some of us don't even use this stuff, but that's because we're lucky enough to have low chlorine municipal water supply. Of course this can easily change at any moment if there is a bacterial outbreak or something like that, but we just play the odds of Russian Roulette. Barbarians such as as Dave "Visigoth" Spencer have been excommunicated from the Church of Rome for publishing heretical tomes such as: Anybody Else Given up on Dechlorinating?

Cheers,
 

Garuf

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Ceg, I know this is directly related but what's the best way of neutralising heavy metals, or at least bringing them down to invert safe levels? I have high levels of copper from the tap and it means inverts are pretty much a no go.
 

ceg4048

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Hi Gareth,
Well of course the best way is to use RO, because that removes just about everything, and the next best way is to use the multi-stage HMA similar to that shown in the link in the first post and that described by Darrel. I'm not aware of any commercial additives that bind with or neutralize heavy metals.

Cheers,
 

dw1305

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Hi all,
I know this is directly related but what's the best way of neutralising heavy metals, or at least bringing them down to invert safe levels? I have high levels of copper from the tap and it means inverts are pretty much a no go.
Again as Clive suggests the best way is to stop them getting in in the first place. If you don't want to use, or can't justify the cost of R.O. I'd strongly recommend rain water, you can always carbon filter it and treat it with a de-chlorinator if you are worried about the quality of it.

You can chelate heavy metals with something like EDTA (probably why Prime etc work), and this naturally occur where you you have dissolved organic carbon compounds (DOC) in the water or humic substances (peat for example) in the tank. EDTA has a high affinity for Cu & Pb, unfortunately the ion most strongly bound is Fe, so if you add iron it will displace the Cu, Pb etc. and return them to their potentially toxic ionic form. Have a look here for a "real world" application of EDTA <http://www.envirofacs.org/Pre-prints/Vol 42 No 2/.../p 116.pdf>

This is from Brett the "Skeptical Aquarist" page on chelation <http://www.skepticalaquarist.com/docs/water/chelation.shtml> tells you what you need to know without venturing into the world of "ligands" etc. It is a low tech., natural solution to the problem, but it does work.
Biosorption. Fishkeepers have often noticed that poisoning due to heavy metals is rare in well-established planted aquaria, where plenty of humic floc incorporated in the substrate chelates them. There is a further biological component to this aspect of "chemical" filtration: heavy metal ions also adhere to the cell walls of biofilm microbes and in the gummy biofilm itself. In experimental wastewater technology, microbes are even being deliberately cultured, to "filter" heavy metals from industrial effluents, a process called "biosorption." As you see, chemical filtration can't always be separated from biofiltration.
cheers Darrel
 

ceg4048

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George Farmer said:
I think most de-chlorinators claim to neutralise heavy metals. How effective they are; I have no idea!
Hmm, could be something to the claims, or it could be total hogwash (which is more typical of The Matrix). Most of the dechlor agents, the ones that don't bind the ammonia from chloramines, use Sodium Thiosulphate (Na2S2O3), but I'm not sure if the thiosulphate by itself can precipitate the metals directly.

The metal precipitation may perhaps be done by adding Hydrogen Sulphide H2S, which is highly toxic. This is the rotten egg smelly gas produced by anerobic bacteria some people experience with stagnant substrates, and that can do a good job of removing heavy metals. Maybe the dechlors have some additional agent that binds with the end product of the thiosuphate/bleach reaction to form H2S. But then the product would be rendered toxic if this were the case. Typically the thiosulphate works by reacting with the bleach in the water (hypochlorite, OCl-) to form harmless chloride (Cl-).

Unless the particular dechlor product uses some other active ingredient I reckon the reactions are strictly limited to hypochlorite neutralization.

Cheers,
 

dw1305

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Hi all,
Hmm, could be something to the claims, or it could be total hogwash (which is more typical of The Matrix). Most of the dechlor agents, the ones that don't bind the ammonia from chloramines, use Sodium Thiosulphate (Na2S2O3), but I'm not sure if the thiosulphate by itself can precipitate the metals directly.
No I think you are right, it is not the sodium thiosulphate, if you look at the ones that claim bind heavy metals it says "contains hydromethane sulf(ph)inate and EDTA" or similar.

cheers Darrel
 

Dave Spencer

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Dan Crawford said:
Yes it's fine IMO
I never dechloronate....

OK, I have some tar bubbling away nicely. Anybody got the feathers?

Dave.
 

ceg4048

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dw1305 said:
Hi all,
Hmm, could be something to the claims, or it could be total hogwash (which is more typical of The Matrix). Most of the dechlor agents, the ones that don't bind the ammonia from chloramines, use Sodium Thiosulphate (Na2S2O3), but I'm not sure if the thiosulphate by itself can precipitate the metals directly.
No I think you are right, it is not the sodium thiosulphate, if you look at the ones that claim bind heavy metals it says "contains hydromethane sulf(ph)inate and EDTA" or similar.

cheers Darrel
OK, so they add a chelating agent to bind the metals. Fair enough then. Thanks for clearing that up Darrel! :thumbup:

Cheers,
 

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