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How soft is TOO soft?

louis_last

Member
Joined
23 Nov 2008
Messages
343
Location
Edinburgh / Dunbar - Scotland
I used to live in an area where we had well water that was essentially liquid rock, I would run about 5L at a time through a distiller for the misting system on my emersed setups and even from that little water a thick mineral gunk was left behind after all the water had evaporated. I kept Boraras in the well water just fine and they even surprised me by producing a single fry that survived to adulthood but now I'm living elsewhere and I have really soft water. I never realised just how soft until today but out the tap it's 7.81mg Ca/L, 0.46mg Mg/L and 21.38mg CaCO3/L.
Fortunately all of the fish I have at the moment are soft water fish but is there such a thing as too soft? Would I or my plants and fish notice any benefit from raising the hardness just a bit? I haven't noticed any of the fish or plants I keep showing any signs that they're struggling other than some Bucephalandra that had much prettier colours in the hard water where the leaves had a sort of blue sheen and in the soft water they are a much duller greyish green - but it grows fine.
It seems I could double these parameters and still consider my water to be "soft" though - might there be any benefit in doing so?
Also am I right in thinking cherry shrimp pretty much won't breed in water this soft? I've had a few amanos and some cherries for a couple of months that seem to be OK, I give them a small amount of cuttlebone as a calcium source but they are all adult size and there's no sign of the females getting berried. Would something like shrimp king mineral food or the shrimp mineral balls allow them to breed in such soft water? And would offering them a mineral rich supplement like that have much impact on the overall hardness of the water to the detriment of my soft water fish if I moved the cherries in with any of the fish?
Are there any other considerations with such sot water that I might be overlooking?
 
Your shrimps will be much better off in 18-25 ppm Ca range and 5-7 ppm of Mg range. The shrimps needs both. At the extremely low levels you are quoting above a fail molt will be imminent and their exoskeleton will be very fragile - they may be able to get by with a diet super rich in Calcium (such as the cuttlebones your given them now), but it's probably not sustainable, and they probably wont breed regardless of diet until you raise the Ca and Mg levels... The good thing about your situation is that it is fairly easy to remineralize your water with a bit of CaSO4 or CaCl2 and MgSO4 or This to make it easy- just make the change slowly.

Cheers,
Michael
 
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I'm not is shrimps. Yet I've noted some breeders say it's not the water but shrimps' diet which is decisive. Can anyone elucidate this question?
 
I ran my blackwater tanks at around 15 TDS for a year in order to match the native environments of parosphromenus and boraras. The fish did well, and the plants that grew well for me were mosses, water sprite, salvinia, hydrocotyle leucocephala, and mayaca fluviatilis. I was unable to keep any inverts alive in these tanks, however, not even asellus aquaticus.

I’ve since learned of a paros breeder who keeps his tanks at 80 TDS, which is apparently low enough for them to breed and high enough for caridina to survive alongside them. This is heresy among paros keepers, but it seems to work for him.

I now run my paros tanks at 80 TDS (adjusted slowly) and my dario tanks at 140 TDS. I keep neos and tangerine tigers at 140, and only the tangerine tigers at 80. This is a relatively recent shift, but it’s based on the success of others. I expect the plants to do better as well.

Whether you “should” increase your water hardness depends on what you want. If you want the neos to breed, it may be necessary. Whether it benefits fish depends on which fish we’re talking about. Your darios likely come from water that is bit harder. Do they care? I don’t know.
 
I moved from liquid rock to liquid liquid? And I’ve wondered this too.

There is a nice thing with low TDS tanks that algae seems to be a bit less? I miss the mini ecosystems I’d have in hard water, but it is what it is.
 
I'm not is shrimps. Yet I've noted some breeders say it's not the water but shrimps' diet which is decisive. Can anyone elucidate this question?
The main source of calcium used to build their exoskeleton is exogenous - that is, the preferential uptake is through the water. If they don't get enough through the water they will need to get it from their diet. If the diet becomes the main source of Calcium they may end up with deficiencies of other important nutrients such as protein. I don't think the amount of Ca and Mg in the water is cut in stone, but if there is enough in the water (not too much as that can be just as bad making molting difficult or even impossible) you don't have to worry about it and can concentrate on keeping your shrimps well fed with all sorts of other important nutrients. Some people around here seemingly keep happy shrimps at fairly low Ca levels (~15 ppm). As with all livestock, there is definitely a range... between survivability at one end, and the shrimps thriving and breeding at the other end. Unlike plants, it can admittedly be difficult to tell with livestock if they are just scraping by or if they are truly thriving.

Cheers,
Michael
 
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I moved from liquid rock to liquid liquid? And I’ve wondered this too.

There is a nice thing with low TDS tanks that algae seems to be a bit less? I miss the mini ecosystems I’d have in hard water, but it is what it is.
This has been my experience too. With the well water I was always battling multiple kinds of algae, it didn't take much to tip a tank from 'a bit of algae' to a full blown outbreak and I was constantly dealing with BGA. In the very soft water from belmore the only algae I encounter is some kind of very blue staghorn algae that grows very slowly and I've actually come to quite like it. It has much larger branches than staghorn I've encountered before that are semi transparent and inside you can see some sort of internal structure that almost looks like a double helix (I know it's not the DNA) unning throughout them. In the tank it looks sort of blue/grey but when I remove it under a bright light it's really very blue.
The well water I had been using also contained a LOT of iron and that may well have contributed as well.
 
This very soft water is what they bred in and fry raised to maturity in it seem fine but if I knew they would do better in harder water I would definitely want to amend it.

Since there's a lot of temporal variation in water parameters in their natural habitat, I would guess that raising the hardness slightly would have little to no noticeable effect. If you felt that the fish would benefit from cohabitating with inverts, that's not a bad reason to increase hardness. Otherwise, I would probably keep things as they are, since using your current water is both convenient and effective.

For me, switching to slightly harder water was more convenient, because soft, alkaline water comes out of my tap. Great for Darios. The paros still take RO, I just remineralize it now.

-B
 
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