Losing fish at wc time

[RD.]

I typically add the water conditioner at about 50% full

This is most likely your problem.

While you're waiting for your tank to fill to 50%, your fish are all being exposed to whatever disinfectant residual is in your taps. Chlorine is toxic to fish. Chloramine is toxic to fish. Do you happen to know what your tap water residual is?

 

[xraycer]

Ic that makes sense I will cut back to 30% weekly from now on. Is there anything I can do to minimize losses now. Normally I would change more water to dilute whatever the issue is but obviously that would be counterproductive with this

Your nitrate level should be what dictates how much water change you should be doing. I don't know your stock level, but I can't really see 30% weekly as being enough to keep up with nitrate buildup....unless you're utilizing plants. But, like I said, it should be dictated by your nitrate level.

I'm fortunate that I have well water and don't need dechlorinator, so I can do large volume w/c (50% every 3 days) without worries from chlorine/chloramine poisoning. But, many members here do 70%+ w/c with city water added directly to the tank, with dechlorinator, and have never had an issue. Of course, dechlorinating water in a separate vessel, would be the safest approach, but not really convenient or not really necessary. So, its a personal choice which leaves it up for you to decide.

In regards to the garden hose, it is another one of those debatable thing. Some feel that a typical garden hose could be leaching plastic which could be detrimental to fish health and that a potable drinking water hose should be used instead. I use the plain old garden hose and I'm comfortable that its fine, but once again, its up to you to decide.

 

[xraycer]

In regards to the poster advising to only clean your filter no more than once a year, I'm going to advise you to clean your filters often. My goal is once a month, but life often gets in the way and I end up sometimes not getting to certain ones for a few months. But since I do plenty of w/c and all my tanks are overfiltered by multiple units, it never gets sludgy or smelly even after 3 months.

 

[RD.]

The garden hose issue stems from the fact that many of todays garden hoses contain toxic elements (algaecides etc), that can leach from new hoses into the water. I've posted a few links about this in past discussions where mysterious deaths took place, and the only new thing added to the equation was a garden hose that was just purchased.

 

[-DC-]

Just my thoughts but chlorine is very unlikely to be the problem , potable water shouldn't carry enough chlorine to do anything more then an irritate the fish , far from lethal exposures. I would recommend adding the dechlor before the refill not halfway through but I still doubt it's this issue that more to protect the benificial bacteria in your substrate , The chlorine can/will damage beneficial bacteria which in turn can cause ammonia spikes . This can be avoided by cleaning your filters using tank water before the change and turning filters off while refilling . I don't think this is the current issue but it's something to consider . As for frequency of cleanings I find it's a personal preference I only do them if flow slows but as long as it's done properly extra cleanings shouldn't harm anything.


From your explanation I right away though PH shock .its an incredibly common cause that very few people ever seem to talk about . I suspect your tap water ph fluctuated. I find after the city flushes/shocks the system or sometimes during a really wet spring the tap water ph plummets . In my city it happens every spring for about a week so it seems to hit randomly unless you happen to notice the trend and think to test the ph when the deaths occur. The swing in ph combined with a BIG water change will result in exactly what your describing .

My advise is to limit your water changes to no more then 25% , this should be small enough to limit any low oxygen or ph issues . If 25% isn't enough do more frequent changes not larger ones. I ran into the exact same problem and learnt my lesson after loosing many beautiful fish. Big water changes can often be fine but parameters might change suddenly and you won't know unless you test every time so it's best not to risk it.

 

[RD.]

The OP never stated that his water supply uses chlorine. In fact, some areas of the US have as high as 4 ppm chlorine and/or chloramine in their supply lines, at least where levels are recorded by the local municipality. IMO chlorine/chloramine exposure is a far greater risk than a shift in pH, and typically when pH values shift it is the change in TDS that kills the fish, not a change in pH. Not nit picking, just sayin ....


I posted the following a few yrs ago ......


Both chlorine &/or chloramine can cause long term damage & even death to fish, in some cases even at low levels, especially young fish which are typically the most sensitive to these substances. Free chlorine can cause acute necrosis of gill tissue in fish, the younger the fish the worse it can be. In short chlorine is an oxidizer, that can burn a fishes gills & kill cell tissue, sometimes even at low levels.

The amount of chlorine and or chloramine can vary greatly from one municipality to another, as well as from one tap to another, and can also vary greatly throughout the season. There is no way that anyone on a public forum can possibly attempt to tell you what a "safe" amount is in your case unless they have the specs on your local tap water at your user end. Water temp, pH values, etc can also determine how 'safe' certain levels of known toxic substances such as chlorine/chloramine can be on fish.

According to Edward Noga, a professor at NC State that is considered an expert in the disease & health of fish, chlorine levels as low as 0.10 mg/l (which is very common in many tap water levels) can be acutely fatal in aquaria that has low levels of organics. (as in a new set up) Others have found residual chlorine levels as low as 0.05 mg/l to be toxic to certain species of fish. Many areas of the USA contain 2-4 mg/l of either chlorine, or chloramine.

There has been a TON of work done in this area over the past few decades, by a number of researchers, such as Tompkins & Tsai (1976) for anyone that is interested in understanding just how toxic both chlorine & chloramine can be in a closed system that contains fish.

 

[Guapoteguy291]

I know there is chlorine in my water. As for the levels I have no idea

 

[duanes]

I agree with xraycer about filter cleaning. When I did studies using microbiological and mechanical data in the lab on filtration efficiency, we found our biological filters needed to be cleaned every 4 days. When not, harmful bacteria began to edge out the beneficial ones, and although water would appear clear, the water chemistry suggested buildup of nitrate, aldehydes and other non beneficial components.
Rinsing gunk out of biological media in tank water, regularely can only make your BB stronger.
And also agree with RD about the hose. Chemical agents are often added to material hoses are made of to keep them supple, and leach that chemical (especially) if new.
If your hose is old, those should already be gone, and not a problem.

 

[RD.]

That's something that you might want to find out, otherwise using dechlorinator becomes a bit of a by guess, or by golly. Also keep in mind that some municipalities use chlorine for part of the season, and chloramine during periods of turbidity, such as the rainy season or large storms, spring run off, etc.

 

[Guapoteguy291]

I've been using the hose weekly since April last year with no problems till last week