Flashing Hell

[Joek101]

I'm at my wits end with a flashing problem in my aquarium. Its been present for pretty much the whole of the last year since i set the tank up. Tank details are as follows:

c.1000 litre tank with 250 litre sump
Ammonia - 0
Nitrite - 0
Nitrate - <10
PH - 7.2
GH - seems to vary between around 3dGH and 5 dGH
KH - 1dKH
Temp - 26 degrees

Water changes generally have been doing around 40% once a week. Pump out water and fill directly into aquarium from a mixer tap (match temperature) having first added Prime to the volume of the tank. Also have added nitrate removing resin to the sump in the last couple of months to keep nitrates as low as possible. Have reduced water changes a bit since adding the resin, but no changes noted in the flashing.

Stock - group of c.20 clown loaches varying in size between a couple of inches and 6 inches. Plus around 20 mixed barbs - filament, tambraparni and denison.

Tank decor - unipac limpopo black sand, 3 massive pieces of bogwood and various drainpipe attachments the clowns use as caves.

The problem - all the fish are flashing regularly, and have been for the last 12 months with varying degrees of regularity. Some weeks it can seem to have subsided, other weeks its relentless. Its never manifested into any kind of illness that has visible symptoms on the fish, nor has caused any deaths. All fish seem healthy, feed well, have good colour and energy. The barbs breed all the time, I find babies in the sump every week. However the fish are clearly irritated by something in the water, and its really ruining my enjoyment of the tank just seeing them scratch constantly. I would say lately it has gotten worse and i have also noticed some occasional head twitching aswell.

I've done a lot of reading and i have considered and done the following:

1. Some kind of parasite - I've treated the tank various times with Kusuri wormer plus, and also Fluke Solve. This doesn't seem to have made any difference

2. Ich - i've never seen whitespots, but due to the flashing i considered it might be this. So i treated the tank a number of times with Esha Exit, and also in combination with Esha 2000. This didn't make any difference.

3. The flashing can intensify after water changes. I thought maybe the water direct into the tank, and or Prime could be the issue. So i tried water changing by pre mixing the water in a large container and then adding it to the tank, which took ages due to the volume of water. I also used a different dechlorinator - StressCoat - for that water change. Didn't make any difference.

4. I thought maybe the substrate might be harbouring some sort of parasite or bacteria, i find it hard to clean thoroughly as its sand, and the tank is deep. So i removed all the substrate. Which was a major pain to do, but didn't make a difference.

5. PH swings on the water changes. I know i have a low KH and so if the nitrates build then it could push my ph down, so was thinking maybe the water changes could be causing shock to the fish if the ph doesn't match. But i keep the nitrates super low, and have very regularly tested the ph of the tank over the last year and it never varies, always matches to the tap water.

6. I'm thinking could there be some other type of nasty in my water, that the Prime isn't removing, and considering getting a HMA filter. But i have other tanks where i am not seeing this flashing issue, so that doesn't seem to make sense. So i haven't invested in this yet.

7. I have noticed the gH does seem to move around a few degrees. I'm not sure why, i think it must be fluctuating in the water supply. But i cant see this would be the cause?

8. I thought perhaps the plastic drainpipes could be leaching some sort of chemical into the tank, but the loaches were previously in another tank with these same pipes for several years with no problems, and i would have expected the flashing to drop after water changes if this was the case, as it would remove the contaminant, but it doesn't.

I honestly don't know where to go from here, but its driving me mad. Some people might say well the fish are all healthy, not dying so why am i bothered, but it really does bother me and spoil the whole fish keeping experience for me. Does anyone have any ideas, have i overlooked anything here?

I don't know whether such a service exists, but i'm thinking now the only way i can get to the bottom of this is to get some sort of full diagnostic done on the water, and also take some samples from the fish to check for contamination and potential diseases.

Appreciate any help.

Thanks

[TropicalFishForums]

[blackghost]

I’d try PolyFilter first. If there’s a toxin in the water PolyFilter will remove it.

Could also be anaerobic gases coming out of the sand. Do you keep it well stirred?

[Joek101]

What is a polyfilter?

I removed the sand and hasn't made any difference to anything.