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i have mentioned this on an old topic but no one has answered yet so i thought id try posting here, i had a lot of trouble of fish dying and my kH getting too low, eventually i stabilized the system but fish still kept dying and i couldnt find out why, now i have no fish left. i want to restock and start again but before i did i send the water off for a full analysis. i only know the tolerance of tilapia to the things we test for using the usual test kits but this anlysis shows me having very high sulphates (S04) i dont know if this has come from the lime we have been using?

also the analysis reveals a fair amount of nickel and also aluminium i was wondering if this is an issue and where it may of come from?

any help would be very much appreciated

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All three of the elements you mention are of concern... and you need to identify the root cause...


Are they coming from inputs, one way or another, to your system.... or are they inherent in your source water...


More details please, preferably pictures of your system...


By the way... the analysis shows that there is nothing wrong with your pH... or carbonate hardness...


You say you have been adding "lime"... why?... and what sort/product??

thankyou for the reply Rupert

the analysis is ok in respect to the hardness due to me adding potassium carbonate and lime to increase the kH the mains water is very low kH. my system is a simple tank with hydroton bed above its constant flooding with a bell siphon to drain. i was wondering if anyone knew at what levels the nickel and aluminium are toxic, also our supplier of hydroton recalled all their stock due to the pebbles leaching some nasties (didnt say what) and im wondering if its come from them.

my other topic :

shows the problems i was having in relation to kH and carbonate issues and why i have been adding what i have.

no i havent added aluminium sulphate or gypsum, just potassium carbonate and garden lime which is where i think the Ca has come from. i think i might have to start all over as im worried about the hydroton i have been using.

Peter Shaw said:

My first thought was you added aluminum sulfate but after looking at your test results your aluminum reading is in ppb (ug/L while ppm is mg/L) so divide 7.2 by 1000 and that is ppm,

I dont know if 0.0007ppm is toxic to fish

Your analysis shows elevated Ca and SO4.... relative to other nutrients

Might you have added gypsum? Gypsum is not a liming material,

Gypsum has many uses, but people often think that because it have lots of Ca it must be a lime.....

CaCO3 and others are limes which are used to raise the pH (and to add Ca),

they raise the pH by neutralizing excess H ions.

But its the CO3 or OH in a liming material that neutralizes H making water, and the Ca remains behind,


If the hydroton (if it is really hydroton) has been recalled, then I would be suspecting it.  Now if you also have a test done of your source water to see if you tap water levels are different than the samples from your system, it would help to isolate if your problem is due to the water itself or something leaching in the system.

yeah i have one ready to go on the next load of water analysis we send off. and the hydroton is definately really hydroton, i have been working with the stuff for 6 or 7 years now.

Great.. a test of your source water is a must IMO...


Hydroton is basically inert... and I've never heard of it being a problem.. or ever recalled...


I wonder if it's possible that your supplier might be selling "used"/"recycled" hydroton...

i have no doubt it is brand new, real, unused and non-recylced hydroton. i am involved in the hydroponic and greenhouse industry here in the UK and im very familiar with all the expanded clay media here especially hydroton. i know my supplier has since released theor own brand of clay pebble and i would have my doubts as to the possibility of them saying its been recalled so we have to buy their one if it wasnt for the fact that they have credited us for all the hydroton we have (pallets and pallets of the stuff) and have said do not sell it. its cost them a lot of money to do that.

i just really need to be sure its not the hydroton otherwise i cant put anymore fish into it and my media bed which is at least part way to becoming mature will need to be replaced and start from the very beginning again.

If that's the case Ian... and I wouldn't certainly like to confirm it...


They should be able to provide you with official documentation advising of the recall... and the specific reasons for it...


Ask them for it... please..

Actually I remember you raising this in early April Ian... on another thread... and I suggested then that you ask for a "recall notification"...


I have googled to find any mention of it... with zero results... and have asked both the major importers and my suppliers here in Australia if they knew of any such recall.... and both replied that they had no knowledge of any recall...


Nor can I find any reference, or press release on the "oekotau easy green" manufacturers website... and to the best of my knowledge... any product recall must be publically advised .. and published by the manufacturer..

Could it be your water temp?  All my fish died too, because I live in South central TX and I think I cooked them.  Inside temp of greenhouse-130 degrees!

here are the results from my water analysis of our tap water, as you can see the sulphates have not come from there. so now im not sure where they have come from. could it of come from the lime i added? i have only added that and potassium carbonate.


Margo Searls-Begy said:

Could it be your water temp?  All my fish died too, because I live in South central TX and I think I cooked them.  Inside temp of greenhouse-130 degrees!


no my water temp is all good i live in the UK so it needs heating more than cooling, thankyou for the reply though.

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