What to use to lower ph to 4

[TCMontium]

I have an aquarium with neutral sand, neutral filter material, some semi-dense planting, a couple of coconut caves and some dead plant matter in a corner. I used only RO water (ph 6.0-ish, "TDS" 20) for the whole one and a half years that this aquarium was set up.
And finally, my water parameters righ now:
TDS 40-50
Ph 5.0-5.5
dKh 0-3
dGh < 3


Now I own a pair of Dicrossus filanentosus and I plan to breed them. How can I lower my ph and condictivity enough (I guess it should be ph 4.0 and TDS 10 or so for D. filamentosus)?
Can I lower them all with peat and almond cones without having negative effects?
Maybe using some tea?


I don't really want to use concentrated acids (I do have chemistry classes but my notes at acids, bases and titration are awful )

 

[Mike Wise]

Do you really need to lower the pH? Many hobbyists have successfully reproduced D. filamentosus with your tank's parameters. Using peat, etc. should lower your pH somewhat, but expect it to raise the conductivity a bit. I don't know why, but your RO unit produces slightly higher results than mine. Tested mine yesterday: pH 5.6, cond. 5 µS/cm (~10-15 ppm TDS). pH will fluctuate more in soft, unbuffered, water anyway. Personally, I'd just add some peat or cones to stain the water a bit and try what you are using now. BTW, I know you won't like hearing it, but I produced D. filamentosa fry in my tank-aged tap water back in the 1980s. I don't know if my tap water is still good enough to do that now.

 

[TCMontium]

Thanks Mike!
I read in many websites that people could only manage to make the eggs hatch into larvae at ph lower than 5.5 or even lower than 5.0, so that is why I felt the need of lowering my ph even more. There is also the "filamentosus are encountered in wild at ph as low as 3.5!" deal. Some say that they will reproduce at around ph 5.5 but the hatch rate will be very low?

My tap water has ph 7.5-ish and TDS 250-ish. Also A LOT of other high values of chemicals. Maybe that is why my RO doesn't give more of a "pure" water. We don't (*can't) drink tap water in Turkey. Maybe I just have a kinda crappy RO device.

I appreciate everything, don't really have a reason to not like your experience with breeding some awesome fish that I also am trying to breed. Though, probably your tap water was better then what I have.

 

[Mike Wise]

I think you might be reading some older literature. Many older (50s - 80s) books, particularly those by German aquarists, wanted water that was almost sterile. That meant a low bacterial load. This was more easily accomplished by using water that was acid and soft. Soft, highly acidic waters in the Amazon do have a lower bacteria/fungi count and overall are less fertile biologically than those with more moderate values. The eggs of blackwater species do not seem to resist attack by bacteria and fungi spores nearly as well as do eggs of clear/whitewater species. This is probably an adaptation to their sterile blackwater environment. In evolution, if it has no benefit, it is removed. We see this not just in cichlids but other fish families. I, for example, found breeding Cardinal Tetras no more difficult than breed Von Rio/Flame Tetras, once I provided the right environment. For me, I find that blackwater species like D. filamentosus live in extreme water conditions because they evolved to deal with it, possibly to avoid more predation of their fry or themselves from other fish. Many happily live and breed in less extreme water values when given the chance. If I were you, I would try to breed your D. filamentosus in your present tank water value, but add some humic/fulvic acids with peat/leave/cones to lower the bacteria count. If that doesn't work, then lower the pH, which should also lower the bacteria count.

 

[TCMontium]

I added some cones and a catappa l eaf into the aquarium and did some RO water change. This morning I found the female guarding eggs (and cornering the male, scaring him shitless! I removed him.). They were not many and almost completely see-through. The female was checking them every 15 seconds or so. Then I went out of home.
Unfortunately the eggs were gone when I came at night (lights were still on, but they are scheduled to turn off for 3 hours around noon).

TDS 60 ppm = conductivity 130 µS/cm (approx.)
Ph is lower than 5.5 (I don't know exactly how low right now)
Gh is lower than 3 dh
Kh is lower than 3 dh
Temperature is 27 Celsius degrees (approx.)
Black gravel bottom
Java fern leaf as egg-lying material
40x40x35h cm aquarium (approx. 45 liters) (a bit small, but the pair is not aggressive)
4 sub-adult Sturisoma aureum, 1 adult Farlowella vittata, 2 Otocinclus macrospilus are the tank mates (they did not bother Apistogramma eggs and fry, but maybe Dicrossus eggs are in the open, so they can eat them more easily?)

So, any ideas about what the problem cause of the disappearance of eggs could be? The female has her brood dress still and she drives the male away. (I did put the male back in tonight.)

Sorry for writing so much and complicated. I am not a native english speaker and my thought-process is a bit clumsy, I suppose.

 

[gerald]

It's possible the eggs were not fertile, and the mother may have eaten them when they started smelling bad. Or, she might have eaten them if the Sturisoma or Farlowella was trying to get them and she couldn't keep them away. (It's better to "recycle" the nutrients and try again later, than to let a predator eat your eggs). There are many possible reasons; all we can do is guess and hope for better luck with their next spawn. Young pairs often have several failed attempts before they succeed. Removing the catfish is probably the best thing to improve their chances. Also leave a small light on near the tank so it never gets completely dark at night.

 

[boofeng]

That's interesting, TCMontium. I've no idea why your dicrossus ate the eggs. My candidi female always gets ripe and full, then disappears somewhere to (I guess) lay eggs, but always emerges a few days later without fry. She used to spit whitish things (fungused eggs?) out of her cave, but now I don't know where she lays. I'm beginning to think maybe my male is infertile - he's quite big, almost two inches I think - so the eggs never get fertilised? Or maybe he's too big to get into whichever crevice she's laying the eggs in.

On adding humic substances (ketapang leaves, almond cones, peat, etc) to induce spawning, my sp. "Abacaxis" began spawning in a tank that used to be pH 7, TDS 200-250, dGH 9, dKH 6, a couple of months after I began doing my water changes using peat-filtered water (pH 4.5 or less, TDS 80-110, dGH 3, dKH 0). The spawn sizes are small though - and fry mortality seems high. The first batch was about 15 fry, and they died when I went on vacation. The second (current) batch is about 10-15 fry. I'm suspecting the eggs/fry don't all survive because the water parameters aren't really suitable...

I recently read this old paper (hat-tip to Darrel for always mentioning these studies ), about the effect of humic substances on cardinal tetras in low pH waters. Interestingly, [low pH + no humic substances] is quite different from [low pH + humic substances], for the uptake and retention of sodium (Na+) and calcium (Ca++) ions. When kept at pH 3.7 without humic substances, the tetras lost Na+, and did not increase their ability to uptake Na+ and Ca++, . When kept at pH 3.7 with humic substances at Rio Negro levels, they increased their ability to uptake both Na+ and Ca++, and retained higher levels of Na+ in their bodies.

Also, I came across an Australian study where Caridina sp. shrimp experienced severe mortality when pH was reduced to 3.7 without humic substances, but show some ability to survive when there were also humic substances in the water. Another study found that daphnia fed a poor quality diet (baker's yeast) show improved lifespans when humic substances are present, though humic substances had no effect on daphnia fed a good diet i.e. microalgae.

So, it seems like humic substances are quite an important factor for fish health and breeding, and I've become a huge fan. In fact, you might say that, to me, they're the new black!

 

[SpotOn88]

I do not believe that you need to lower your pH to that level

I had wild caught Dicrossus Foirni and they reproduced successfully in the following water parameters:

Temp 25/26 degrees celsius
pH 5.2
dKH 0
dGH 1

It was a black water tank with a substantial amount of driftwood and leaf litter on top of the sand substrate. I also used eheim peat in the tank (& RO water obviously)

I'm now a proud owner of 4 x F1 Dicrossus Foirni that are 7 months old.. The female was in my opinion an excellent parent and managed to successfully raise 9 from 30 free swimming fry

Good luck