Fighting the BGM

[Aleman]

Ok, so after a big clean, and a couple of water changes, the bl**dy BGM is back! So the last two days have seen me do two 50% water changes back to back, plus run my SunSun canister filter as a "vacuum cleaner" for a couple of hours while I made sure that I removed as much slime, and detritus as I could with a gravel cleaner attached to the inflow. I can see that I'm also going to have to cut my carpet plants back (Montecarlo and S. Repens). I've removed the L. brazilliensis, and will probably remove the Eleocharis "mini" as well, split them up and replant. I've had enough trying to grow red plants (A. reinekii , and L. repens), so the remains of the Ludwigia will be removed, the Alternanthera melted long ago, and I'll fill the space with a couple of echinoduorus ... I already have E. horemanii and echinodorus "Reni" so I've decided on echinodorus "Red Diamond", which although is technically a red plant, it's similar to the Reni, which is actually growing well, if not very large ... it is a slow growing echinodorus after all.

You don't have to get all mathy here about 25+25 ≈ 50. If you do a 50% water change and think you stirred up organics/debris or whatever go ahead and immediately do another 50% water change.

Great idea, assuming the RO unit has caught up ... Actually it's more than possible, as I fill a 300L IBC container for water changes ... Remineralize and add ferts .... Hmmmm ... I might get on top of this bloody menace 🙂

I've got a question about ferts though. I use RO water for all my water changes, and remineralize to 1dKH and 2dGH. I'm following a "modified" EI regime, ( Nitrate 30ppm as KN03 and Urea 2:3, 3ppm Phosphate and 10ppm potassium as K2HP04, magnesium 10ppm as MgSO4 ), dosing the following every day (a total of 50ml each day, as 10 by 5ml doses every 2 hours - coz I can ... autodoser 😀 )

Macro - nitrate 4.3ppm, phosphate 0.43ppm, potassium 1.43ppm, magnesium 1.43ppm and sulphate 5.65ppm
Micro - iron 0.71, manganese 0.017, zinc 0.014, boron, 0.008, copper 0.002 and molybdenum 0.0013ppm)

125l weekly water change remineralised using MgSO4, CaSO4 and KHCO3 to hit 2dGH, 1dKH, 3:1 Ca to Mg, and 14ppm potassium.

So to my question, the autodoser is running as it should before and after the water change. When I do a big one, say two 50% WC's back to back should I add additional ferts, perhaps half a weeks dose dry dosing to restore the levels??

One other set of data that might be of use, as it shows that perhaps I'm under dosing some nutrients are my water test results.
4 dGH, 2dKH, ammonia zero, nitrite 0.069, nitrate 5, phosphate 0.6, iron zero, potassium 28. pH is set to 6.15 + or - 0.1, temperature 25C.

 

[Hanuman]

use RO water for all my water changes, and remineralize to 1dKH and 2dGH.

Unless you have specific needs I wouldn't even bother dKHing, yeah I made that word up right here, right now.
I would bump that dGH to a good 4ppm. 2ppm seems a bit low in my opinion considering you have some inverts in there.

I'm following a "modified" EI regime, ( Nitrate 30ppm as KN03 and Urea 2:3, 3ppm Phosphate and 10ppm potassium as K2HP04, magnesium 10ppm as MgSO4 ), dosing the following every day (a total of 50ml each day, as 10 by 5ml doses every 2 hours - coz I can ... autodoser 😀

IMO, although urea can be good for plants, it is unnecessary and can expose you to problems with algae. For Mg I would go for a little less, say 6-7ppm or so, while Ca at ~ 20ppm. That would be a traditional 3:1 ratio which is pretty standard and gives a you ~4dGH. Small rule of thumb: equal amounts by weight of CaSO4 and MgSO4 equates to a 3:1 ratio.

So to my question, the autodoser is running as it should before and after the water change. When I do a big one, say two 50% WC's back to back should I add additional ferts, perhaps half a weeks dose dry dosing to restore the levels??

if you do 2 WC back to back that would equate I believe to a 75% reduction in ppm values. That is where adding ferts with ammonia/urea is tricky because you would need to add substantial amounts of ferts to recover the initial levels. If I was you, I would quit urea unless you really are using it for a specific reason, which honestly I can't see one, use only Nirates and front load all those big boys NO3, PO4, K, Mg and Ca at once at every WC. Then daily dose traces. When you front load, calculations have to be on WC volume, not tank volume obviously.

One other set of data that might be of use, as it shows that perhaps I'm under dosing some nutrients are my water test results.
4 dGH, 2dKH, ammonia zero, nitrite 0.069, nitrate 5, phosphate 0.6, iron zero, potassium 28. pH is set to 6.15 + or - 0.1, temperature 25C.

Test result from where? You sent your water for a lab analysis? Honestly I don't see much the point in doing that if you are using RO. But regardless, it is showing low levels of Nitrate and phosphates. Those should be higher IMO. Iron at 0 is no bueno. Potassium at 28 doesn't shock me.

My only concern with your micros is that you are using CSM+B. Can be hit or miss.

For your BGA issue, make sure you have a good oxygenation of the water. Try buying through ebay or the like some Chemiclean to give the bacterial a good slap on the face.

 

[tam]

I'd still advocate a black out, in my experience you can do a thorough clean so it looks visibly gone and you'll be back to where you started a week later.

 

[Hanuman]

In my opinion black outs do more harm than good. Plant suffer during a black out and you don’t solve the underlying issue. It’s just a temporary band aid. BGA will see a black out like a siesta on a sunny afternoon and will just come back as fast at it left. It’s best to fix the issue, give plants what they need and the rest is history.

 

[Andy Pierce]

Ok, so after a big clean, and a couple of water changes, the bl**dy BGM is back!

Well yes - you haven't changed the underlying conditions in the tank so things go back to where they were - something has to change to sort out the cause of the problem (this is also why a blackout won't work). Everyone has to find what works for them (my current is at Estimative index - Fireplace aquarium and I'm pretty happy) but adding urea seems unusual to me and your water is very soft - is there a reason to keep the GH and KH as low as what you're aiming for? I use Cambridgeshire tap water and per test strip the aquarium GH and KH are both ~ 17, have been for years and don't seem problematic.