Multiple fish casualties

[kiko]

I would just go full on remineralized ro water...
no more surprises from source

 

[Essjay]

When you say filtered water, you mean using nitrazorb to remove nitrate? The website says it removes ammonia, nitrite and nitrate, but as you are using it to remove nitrate before the water is added to the tank, that shouldn't be upsetting anything in the tank. All it means is when you mixed some plain tap water in the new water there was a bit more nitrate than usual.

I can't see anything so far in this thread which could be killing the fish, I'm afraid.





Using RO water would mean no nitrate, but as you have hard water fish you would need to add enough remineralisation salts to get the hardness up to the level needed by your fish.

 

[Characf]

When you say filtered water, you mean using nitrazorb to remove nitrate? The website says it removes ammonia, nitrite and nitrate, but as you are using it to remove nitrate before the water is added to the tank, that shouldn't be upsetting anything in the tank. All it means is when you mixed some plain tap water in the new water there was a bit more nitrate than usual.

I can't see anything so far in this thread which could be killing the fish, I'm afraid.





Using RO water would mean no nitrate, but as you have hard water fish you would need to add enough remineralisation salts to get the hardness up to the level needed by your fish.

Maybe an illness then?

 

[kiko]

you have a tank...a filter...plants and fish and as a UK resident...super hard water
just stop over-doing things...big water changes kill fish more often than people would like to admit...
I've had this debate over and over and not going into details on it but...stick to 20% water changes...need to do more for whatever reason?
do 20% today, 20% tomorrow and 20% the next day...there's no reason to do a 75% water change unless you had an emergency like dropping something in the tank...
now light times...lights should be a single continuous period...as you mentioned having algae before
I would start by having them on 5-6hours a day and slowly increasing it over time to around 10h/day
reasons for having algae? too much light or too much oxygen (flow) or too many nutrients from people overdoing liquid ferts
some people will tell you do a canister at 5-10x turnover...guess what? those people are fighting algae themselves...
now water parameters...most freshwater fish will do fine near a neutral ph/kh...this includes guppies plecos neon tetras corys..shrimp...blablabla
stop wasting money on nitrate filters and whatever store people are suggesting you use...they're in it for the money
now you have a few things you should fix to get things proper...
1. lights at 6h/day
2. 2x turnover flow..(no flow pumps) you can have a flow pump maybe for 30mins/day with a timer pointed downwards to release poop/leftovers off the substrate into the filtration
3. use root tabs for plants instead of liquid ferts...people just tend to overdoit..too many nutrients = algae blooms
simple way to use root tabs is to add 1tab for each 10gal if your plants start melting add 1 more...wait 1 week and check again...when your plants are fine just write down how many tabs you've used and use the same number in 6months
4. fix the water...ideal water is neutral with a ph of 7 and most freshwater fish will do fine with this...instead of wasting money on whatever in-filters...
get a 3 or 5 stage rodi system...they cost around 100 and change
water changes with an rodi system are done in 2 methods...
first method is 100% rodi water and using seachem equilibrium...not the cichlid salts as suggested by some (you have full control of water parameters and 0 surprises)
second method is percentage based...lets say your ph sits around 8.3 and you want to lower it to 7.2...grab a bucket a ruler and mark 20 lines using centimeters/inches whatever you want to use
those 20 lines are basically 5% increments now from 8.3 to 7.2 you do some simple math...(7.2 / 8.3 * 100) which comes to 86.7% since the bucket is measured for 5% increments we'll do 85%
so you fill the bucket to the 17th line with tap water and up to the 20th line with rodi water and voilá! water fixed...
now...you should NEVER make a drastic change like this in a single water change...a water change like this would just kill most if not all of your fish
since you know you want to eventually get to 15% rodi....do a 95% tap + 5% rodi next water change 90 - 10 and after that you can just do the regular 85 - 15 water changes
the 75% water change with 50% filtered and 50% is more than likely the reason your fish died
Be patient, everyone makes mistakes and good luck

 

[Essjay]

@Characf You will find that the vast majority of forum members advocate large weekly water changes. Those who don't are in the minority. Only you can decide which advice to follow.





@kiko Just a heads up - large areas of the UK have soft water. I live in one of them The south east of England is the main region with very hard water.

 

[kiko]

@Characf You will find that the vast majority of forum members advocate large weekly water changes. Those who don't are in the minority. Only you can decide which advice to follow.
@kiko Just a heads up - large areas of the UK have soft water. I live in one of them The south east of England is the main region with very hard water.

not the ones in this forum xD
all the time I just see people complaining about super-hard water...
as for the water changes...I've been in a few debates over this..and the fact is..more often than not...people just kill their fish by doing so...
either being a drastic change in water chemistry...temp not matching shocking fish...overdoing chemicals with water-changes and so on...
I'm yet to see someone using a python hose with a close valve at the end into a sink with a thermometer...the "finger feel" doesn't match temps but works at smaller changes xD
but I'll leave it at that...we've had these discussions before in this forum and at the end it's a matter of preference

 

[Essjay]

I do water changes using buckets so I am able to add the correct amount of water conditioner for each bucketful and I can adjust the temperature in the bucket before adding the water to the tank. I know many people swear by pythons making water changes easier, but I prefer the bucket method even if it is harder work.

 

[Naughts]

When you say filtered water, you mean using nitrazorb to remove nitrate? The website says it removes ammonia, nitrite and nitrate, but as you are using it to remove nitrate before the water is added to the tank, that shouldn't be upsetting anything in the tank. All it means is when you mixed some plain tap water in the new water there was a bit more nitrate than usual.

I can't see anything so far in this thread which could be killing the fish, I'm afraid.





Using RO water would mean no nitrate, but as you have hard water fish you would need to add enough remineralisation salts to get the hardness up to the level needed by your fish.

Thanks, for some reason I thought the Op had used a pozzani filter to prepare tank water so had changed the TDS/ organics.