On the other hand, are you assuming that your DO is high? Have you verified? DO is a difficult parameter to measure and the solubility of the gas is very poor. I always assume my DO is poor, so that programs me to do all the things I can to raise it. That's just a personal mindset.
I did attempt some DO tests, I can't find the exact results that were indicated, and I';m aware it is a very difficult test. I do remember that the results were far from conclusive, but indicated that the DO was fairly saturated and not low, but stuffed if I can remember the values for what they were or weren't worth.
Well I think that might be an assumption. You have to allow the plants to tell you what is a waste and what isn't. Higher concentrations of nutrients cause a higher nutrient uptake, so the plants may not agree with your opinion.
Indeed, plants, as well as all living organisms can tell us how they are doing by showing healthy growth. The levels we feed plants at is quite possibly a huge excess compared to nature, certainly as far as water-borne nutrition concentrations go. Is a high level of nutrition (the excess I referred to) beneficial should it not happen in nature?
When flow, distribution and nutrient levels are high then there is better performance overall.
I agree here, although i would change "..and nutrient levels are high" to "...and nutrient levels are sufficient to not be a limiting factor of plant health".
Again, if you are getting good performance from half dosing then that's fine. What I'm saying is that if we self impose limitations on dosing because of a fear of TDS rise then we generally create more problems than we solve. It may not matter so much in this particular case, but generally it's better to worry about having a clean tank and good plant health, because these are much more important.
As we all know, and I'm sure you have said this yourself, there is no correct level of plant nutrition to add to a given body of water, so the half dose that works for one person, may not be anywhere near enough for another, given comparable settings at least. We should not impose limitations on dosing - until such point we see detriment to something in the aquarium. You have testament to elevated TDS and sensitive species, but you will have over time found the correct balance for your tank, and are able to maintain the tank at a stable level of nutrition and at stable parameters. The tank I have been dosing is relatively recent upgrade for me, so I would (now) prefer to start off with a moderate dose of fertilisers, see how the plants and the fish do, and try increasing the dose and make further observations. Doing what I did to begin with and throwing in a full starter dose turned out to be not the best way to commence things, and I should have known better than to do that.
I can't really know what the cause of death was in the case you mentioned. It's always easy to blame nutrient loading for a fishes demise. It's a popular bogie man.
The TDS of the tank could have been constituted of anything, the fact it was plant nutrient was immaterial to the deaths. I don't believe, like you that nitrate is the bogie man as it is commonly villainised to be. I believe nitrate is the smoking gun that appears after a problem, possibly from an ammonia spike or maybe from insufficient water changing leading to poor water quality. What causes it is always the problem, which then leads back to a "who" in many cases. In my case in the instance I refer to, it was me.
It's not clear to me if you are saying that you had fatalities and that at the time the TDS was high due to nutrient loading. Is the assumption then that high nutrient loading caused the fatality? People who keep these fish in unplanted tanks suffer numerous fatalities as well.
The TDS was high due to a known overdose of nutrition, this could have been picked up on if I'd thought to double check what had been stable water (with regards to TDS and EC) up to that point. It was later I realised that TDS was high, and decided to check certain water parameters to find out what was making it high. Again, I don't rely on chemical tests, and don't get them out too often, but I will use them as a guide if I feel it may help build an idea of what is going on a certain time.
I offer these example to challenge the notion, and to argue that we need to look elsewhere for the causes. Unlike you, very few people are aware of BOD and that's why the popular notion of maintaining tank parameters such as pH and so forth are a waste of time, because we have no way of measuring the thing that matters most, and that's why overfeeding combined with refusing to do frequent large water changes causes so many problems.
It is very easy to have a knee-jerk reaction to the loss of a fish, or a sudden outbreak of algae, and water issues are easily blamed, and it very well could be a water issue, but whether it is down to dosing or not is what needs to be investigated by the aquarium keeper before blaming anything. many aquarists are unaware of BOD as well as a whole host of other issues in the aquarium, and many do not want to know, some just want to buy a tank today, and go buy some fish and plants tomorrow and sit back and hope it deals with itself. Hopefully those who don't know about BOD at least know anbd have learned from experienced keepers that rudimentary tank maintenance is key to a healthy aquarium.
I've never kept Parosphromenus, but I have kept discus, rams and other dwarf chichlids and various soft water species at these levels without any problems, so I can't see why these would be any more difficult, but never having done so means that I don't know the answer. Of course, if my objectives were to breed, then definitely I would lower the TDS, but the fact that I observed spawning behavior in some of these fish in community tanks, even with such high conductivity, is evidence that there are other important factors at play.
A little unfair to throw Paros in on my part. Their normal water parameters very acidic, EC and TDS barely register. There's no earthly way they would survive in anything much higher than that, and certainly not in 800µS/cm water. There is much research to be done on the genus though. They do however make delicate softwater cichlids look like very hardy fish. The fish I lost aren't quite as sensitive as the Paros, but do require very soft and low conductivity water. It may be possible that they could be acclimatised over a great period of time to water with a greater salinity, but being wild imported fish of which very little is known other than an elevated TDS and EC can and will kill them very quickly.
There have been some very good points raised here, and to simplify and summarise for those who don't want to wade though the above exchange, I agree dosing may not have an effect on fish, and is definitely beneficial to healthy plants and in turn beneficial to the aquarium.
However, I also stand by that ferts should not
always be dosed in excess, certainly not in the first instance. Increasing fertiliser dosing (slowly) is encouraged of course, but consider what fish you have, and what fish you intend introducing. I'd be uncomfortable introducing a wild caught softwater fish, regardless of its alleged sensitivity in to water that had a very high mineral content compared to the water it had previously been kept in. Any by mineral content I mean either tap water or any aquarium with a heavy dosing regime. I will, especially after recent events, build up my dosing and carry out observations on the aquarium before increasing the amounts.
May I also ask what the plant is in the centre of your top photograph you added to the thread? The photo without the Alternanthera? Thanks
