# Went RO, lost tens of Cories



## Ravenswing (24 Feb 2014)

Hi all!

Sorry, long story...I turn to you with this (at least to me) mysterious case what began last September-October as we started collect rain water for our five aquariums. This was because we have a bit nasty tap water with pretty hight TDS (450-530uS/m) with lots of NaOH and NaCl, other tap water prams GH 4-5, KH 3-4, pH 7,2-8 or more. I bought RO-unit at christmas, after that 50-70% RO, rest from tap. We wanted to keep some more sensitive shrimps and fish species and thought that lowering TDS would be a good idea. TDS was in tanks about 850uS/m when we started the project. We came down to 400uS/m within two months. Problems started, lets say about three weeks after first rain water addings. First cories died. Since that we have lost about 15 C similis (the whole group I had...), over 10 C paleatus, few C concolor (10 left, oooh..not these....I love them!!!), 10+ C sterbai (some of them my boy had grown himself, so sad), 10+ C aeneus... quite many, eh? But however, not a single C trilienatus, Albino Cory (donnou if aeneus or paleatus), C pygmaeus or C hastatus wich I find weird since they are kept as sensitive in general. Shrimps are doing just great, before rainwater/RO we lost nearly all bees, but now they are flourishing. However, we havent lost not a single "swimming" fish, just cories. Plecos are fine, loaches are fine...just cories died. And they just_ die. Some of them turned to be a bit skinny and weak, but most of dead ones we have found...just dead. Yesterday they seemed to be fine, eating etc and next day...dead. Both young and many years old one specimens thou I have a feeling that most of dead ones are older ones. All this happend in two different tanks, not just on one. BTW, I have given worm medicin (Jungle Paracite Clear) in case of worms since some of them lost weight hence good appetite. No improvment.

Any ideas what is going on? I found sons old and huge C paleatus dead this morning. He seemed to be totally fine outside. We`d like to get new cories, but is it worth of it? As fas I can see, nothing else changed in tanks but the water. I use salts for plants so GH/KH is/has been 1-2. Son is really upset, Im confused and sorry.


----------



## roadmaster (24 Feb 2014)

Can only speculate.
Don't think that would be of much help.
Seem's odd that only corydoras species are affected.


----------



## ian_m (24 Feb 2014)

Couple of things spring to mind...
1. If you are using rain water, you have run off contamination somewhere. Read that rain water from a "felt" roof (or even the roofing felt under tiles dipping into the gutter) can cause fish fatal contamination.
2. I assume you have an RO pre-filter to remove chlorine (chloramine) ?
3. You forgot to add dechlorinator to the 50% tap water you are using. I read somewhere that extra chlorine/chloramine is being added to water to cope with any potential contamination (in UK) due to flooding.


----------



## roadmaster (24 Feb 2014)

I should think all fishes would be affected by contamination or chlorine/chloramine poisoning.
More inclined to suspect /speculate,that possibly low O2 level's  might be contributing.
Maybe increase surface agitation.
I have used the antiparasite med mentioned in original post, by making a paste with equal amount of fish food and a bit of garlic extract, water.
Must offer this food and only this food for a week or two (in my view), which in my case,required witholding food's for approx three day's before offering the medicated food.(fish were hungrier then)
I mixed the antiparasite med with a bit of garlic extract, and as mentioned ..equal amount of fish food to form a paste that I then froze.
then I could break off chunk's and offer it to the fish.
Without mixing the medictaed food with regular food's,the fishes would ignore it even after three day's of no other food's being offered.
 I might also wonder if loaches are not a bit quicker at grabbing food's than the cory's  and maybe cory's aren't getting their share?
Most troubles I have had with internal parasites were greatly reduced when I stopped offering blood worm's  on regular basis.


----------



## Sacha (25 Feb 2014)

Chlorine/ chloramine is actually harmless to fish.

It kills nitrobacter and nitrosomonas though, which means it destroys your biological filtration, which in turn will hurt the fish.


----------



## roadmaster (25 Feb 2014)

Sacha said:


> Chlorine/ chloramine is actually harmless to fish.
> 
> It kills nitrobacter and nitrosomonas though, which means it destroys your biological filtration, which in turn will hurt the fish.


 

Chloramine is..chlorine and,,, ammonia.


----------



## Sacha (25 Feb 2014)

Isn't it in the form NH2Cl, meaning the ammonia is bound...?


----------



## Alastair (25 Feb 2014)

Sacha said:


> Chlorine/ chloramine is actually harmless to fish.



Id have to disagree on this one. Chloramine is toxic to fish as it stresses the gills of the fish. 

Yes it does also have an impact on biological media but it is most certainly harmful to fish


----------



## ian_m (25 Feb 2014)

Dealing with chlorine and chloramine | The Skeptical Aquarist


----------



## sparkyweasel (26 Feb 2014)

roadmaster said:


> More inclined to suspect /speculate,that possibly low O2 level's  might be contributing.


As Corys breathe air I would expect them to be the last fish affected by any oxygen deficiency.

I would suspect a disease if only Corys are affected. But without symptoms it's difficult to diagnose.
I suggest you stop using rainwater and make some big water changes and see if the deaths stop. Then at least you would know if the rainwater is the cause and start investigating what is wrong with it. Or that it's not the rainwater and you need to look elsewhere.

hth


----------



## roadmaster (26 Feb 2014)

sparkyweasel said:


> As Corys breathe air I would expect them to be the last fish affected by any oxygen deficiency.
> 
> I would suspect a disease if only Corys are affected. But without symptoms it's difficult to diagnose.
> I suggest you stop using rainwater and make some big water changes and see if the deaths stop. Then at least you would know if the rainwater is the cause and start investigating what is wrong with it. Or that it's not the rainwater and you need to look elsewhere.
> ...


 
 Well,, Corydoras spend most of their time near the substrate where O2 level's may be much lower than that near the surface.\
Also would be more O2 in water with good movement as opposed to stagnant condition's but What filtration the OP is using is unknown.
I have inadvertently created conditon's in my tank that would send cory's/loaches to the surface more frequently than otherwise by forgetting to plug filter back in after maint.
Otherwise the cory's in my tank's seldom rise to the surface.
My apologies for spitballing if you will, with speculation . Really must learn to refrain when it serves no purpose.


----------



## Ravenswing (27 Feb 2014)

Hi all! Sorry it took so long to thank you all, Iv been busy at work right now.

Then...some thoughts and information, thou Im afraid well never know what (has) happend. I guess the only way to get out of this is patince and waiting. No new fish before this is surely over. I didnt assume that I would find The One And Only Aswer (but that would surely help!) but all ideas and observations were/are wellcome.

I have used JBL Biotopol for years as a dechlorinator for whole amount of added new water (RO/rain//tap), not just for tap part, I assume this should take care of chloramines etc.
Suface agitation in the worst destroyed tank is pretty strong, using glut (+other fertz) as we have done with same amount for months, no gaseous CO2. All Ottos are totally fine, so are plecos as written above. Tank is about 130x50x50cm. filtration well matured (2-3 yrs old) HMF with 1000l/h pump plus Aquabee inner filter 1000/l (wich even might be true, the flow is rather strong compared to for example Eheim with similar l/h for example), wich is cleaned regularly once a week, The flow goes mainly towards surface. In this tank albino cories are just fine, but others not so...most of them dead now.

We stopped using rainwater totally at Christmas, since that RO (100-50%)-tap. Deaths still going on, thou last one has happend when I started the thread. Well, isnt this the case when you chedule to a doctors appointment...? The problem is gone. This time: hope so! I havent noticed anything special when it comes to cories, or other fish, behaviour, no sign of any stress, except few cories got skinny before they died. Yet they ate and then...kick the bucket. I think I have pretty knowledge of fish medicins and medication, this time...no idea and surely dont want add meds blindly, especially all other fish, "swimming" ones, are so fine! No new fish for a long time.

When it comes to rainwater, I think that can be the hit. Or not... Roof is made of painted tiles, no glued or nothing, about 7 years old. TDS of rainwater was 7-10uS/m so I thought it is fine to use it thou I know that really doesnt tell you all. I realized it can be risky business. It is also possible that dead cories were injured by polluted rainwater but because of slowly proceeding damages, died lately, after stopping using rainwater. im really afraid of use rainwater (wont) in the future wich is pitty since our water is pretty expensive, we pay over 8euro/m3 so RO is pretty expensive hobby! At the end of this year will get much better tap water so using RO wont last forever. Oh my...I just hope this would be over, so sad for son who has lost nearly all of his cories.

Cheers, Maria


----------



## dw1305 (27 Feb 2014)

Hi all,





> TDS of rainwater was 7-10uS/m


 That is really pure and pretty much what you would get from an RO filter, I think you can discount any direct toxic effect from the rain-water. A thought occurs that if your pH went from alkaline to acid that previously immobilized compounds containing zinc, copper, lead, aluminium etc may have gone into solution. You can chelate most heavy metals with humic and organic compounds, which is partially why I like some dead leaves etc.

cheers Darrel


----------



## Ravenswing (28 Feb 2014)

Hi Darrel!

Yes, thats nearly same TDS as I get from my RO-unit. pH drowned, thou slowly, from about 7,2 down to 6,2 (WC 50%rw-50%tap), pH of the rainwater is about 5,2-5,4. I avoided to use rw about 10-30min since rain started, but still there was sometimes black dust (smutch) from the roof. Could some other water treatment be a better option than JBL Biotopol (I have a big canister of it)? The manufacturer says it should take care of heavy metals too. There is a lot of oak leaves in the tank, both fish and I love em! 

Cheers, Maria


----------



## Ravenswing (27 Mar 2014)

Hi all!

Just one death after my last post so it seems that problem is gone. Only thing that comes into my mind causing the whole mess was low pH combined with fertz. I do fertilize all five tanks but the interrelate thing between two tanks loosing fish was pretty high amount of fertz. I really might be wrong but that is the only difference between two death traps and three other tanks and as I wrote, not a single fish died in those three other tanks. If I can just remember right, pH was less than 6 (5,6? 5,8? Or was it even 5,4?) at that time we used just RW. If Im right, some cory species are much more sensitive to....what?...as Darren suggests above copper, zinc, aluminium, lead or...maybe iron wich becomes toxic when pH lowers if I can remebber correct.That "what" might have come even from the roof too but in that case "what" would have been in every tank I guess. 

Conclusions? Maybe none, but I would avoid lowering pH significantly low (maybe under 6) when using fertz and/or be extra carefull when using fertz with low pH. Just my two cents. On the other hand I could still use RW cutting tap, didint get too scared about this accident, just more carefull.







Cheers, Maria


----------



## RichardJW (18 Apr 2014)

sparkyweasel said:


> As Corys breathe air I would expect them to be the last fish affected by any oxygen deficiency.
> 
> This is not anatomically true - they swallow air and then absorb the oxygen through their stomach walls , the bulk of their O2 is still obtained by usual means I.e. Through their gills . Apologies for being a pedant but I think it helps if we all have a correct understanding of how they cope with their given environment ..
> 
> ...


----------



## RichardJW (18 Apr 2014)

If PH crash is possibly a problem , maybe it's worth having something to help buffer . I've always used a small amount of bog standard gravel - even as a layer in my filter when keeping Discus in a bare tank . Unless you're trying to run at PH 5 for very specialised fish I find it keeps our parameters at 6.5 .


Sent from my iPad using Tapatalk


----------



## Humbert (18 Apr 2014)

Ravenswing said:


> I use salts for plants so GH/KH is/has been 1-2



Hi. was reading your topic when this popped up: what exact kind of "salts" are you using for plants?
cory cats are extremely sensitive to normal salt, if you are using normal table salt, then that's what's been killing your corys.


----------



## OllieNZ (18 Apr 2014)

Humbert said:


> Hi. was reading your topic when this popped up: what exact kind of "salts" are you using for plants?
> cory cats are extremely sensitive to normal salt, if you are using normal table salt, then that's what's been killing your corys.



Normal salt kills plants too.
Most likely potassium nitrate, potassium phosphate, etc


----------



## sparkyweasel (19 Apr 2014)

Where they get the bulk of their oxygen depends on where it's available. In most aquariums that would be from the water. In a backwater full of rotting vegetation a greater proportion would be from the atmosphere.
If there was a shortage in the aquarium water they would compensate by increasing their dependence on atmospheric oxygen, which they do indeed swallow, absorbing it mainly through a specialised epithelium in the hindgut.
[DOUBLEPOST=1397867443][/DOUBLEPOST]Oo-er, quote not showing.


----------

