Turbid / hazy water due to almond leaves?

[MichaelJ]

Hello, the water in one of my 150L (40 US Gallon) tanks is starting to get somewhat hazy and I am trying to understand why. The tank is heavily planted and plants and livestock (shrimps, tetras, otos and snails) are doing great. This is a mature and very clean tank. Maintenance is 40% weekly WC. In addition to tons of plants the tank have lots filtration: Two Tidal 35 HOB filters and two Aquael Pat Mini internal sponge power filters for additional flow and circulation, a surface skimmer and a UV filter (GKM) on a timer, as I only run it a few hours per day. Now, I used to filter over Purigen, and the water was always neutral and insanely clear. A couple of months ago I removed the Purigen as I was starting to add Almond leaves to the tank, mainly to the benefit of the shrimps, and having the Purigen in there would essentially cancel out a lot of the beneficial effects of the Almond leaves. However, even with the expected tinge from the tannins released from the Almond leaves the water remained crystal clear - for a while at least... over the past couple of weeks I've noticed that the tank just won't clear up to the level it did in the past after WCs. It bugs me to the point where I am considering going back to Purigen.

The water in my other tank, which is essentially identical to the tank above, heavily planted as well but without shrimps, as I have Rams and Angles in that tank, remains clear and neutral and I still filter over Purigen in that tank, so I would rule our my water source, minerals, fertilizer etc. as I treat both tanks identical except for the Almond leaves and Purigen.

I am rather new to using Almond leaves so I am wondering if they could be the culprit?

Cheers,
Michael

 

[X3NiTH]

The tannic acid released from the Almond leaves is a massive molecule able to chelate lots of different things including proteins (reason tea tastes dry is all those cages binding with mouth surfaces, more akin to molecular scaffolding), there’s a possibility that the cloudiness is bacteria nucleating on the surface of the tannic acid and making the molecule change its size and/or opacity making it appear visible.

Free metals can also be chelated by tannic acid and these can also change the opacity of the chelated molecule in quite dramatic ways, free Iron chelated with tannic acid will go opaque black (this is Iron Gall Ink, same stuff you’d use in a fountain pen).

Running UV on the system to break the chelate bonds or to reduce any nucleated bacteria build up on the chelate should help to clear this up, of course it can also be mechanically removed using Purigen but it might be too effective and remove the tannins completely.

 

[MichaelJ]

The tannic acid released from the Almond leaves is a massive molecule able to chelate lots of different things including proteins (reason tea tastes dry is all those cages binding with mouth surfaces, more akin to molecular scaffolding), there’s a possibility that the cloudiness is bacteria nucleating on the surface of the tannic acid and making the molecule change its size and/or opacity making it appear visible.

Thanks @X3NiTH Brilliant exposition, as always. I kind of thought along the lines of a bacterial bloom of sorts, and since I am adding the leaves on a regular basis, as they break down fairly fast, I am essentially constantly feeding the bacteria. If that is the case.

Free metals can also be chelated by tannic acid and these can also change the opacity of the chelated molecule in quite dramatic ways, free Iron chelated with tannic acid will go opaque black (this is Iron Gall Ink, same stuff you’d use in a fountain pen).

Running UV on the system to break the chelate bonds or to reduce any nucleated bacteria build up on the chelate should help to clear this up, of course it can also be mechanically removed using Purigen but it might be too effective and remove the tannins completely.

For now I am going to crank up the UV filter and let it run continuously for a couple of days. I am not sure how good the bulb is as I've had it for a long time, but not used it much. When I dose traces I just have to remember to shut it off so I don't reduce the efficacy of the traces (Fe especially).

If that doesn't work I will have to consider adding back the Purigen perhaps just to one of the HOB's and possibly dial down the application of the Almond leaves. Except for the increase in water turbidity, I really like the properties of the leaves though - the shrimps are crazy about them and one nice benefits in this tank, due to low KH (1-2 range), is that the pH has slowly come down to the 6.8-7.0 range - from 7.4 previously, which is beneficial for a bunch of stuff including Fe availability, as you have explained on earlier accounts.

Let's see how it goes. Thanks again.

Cheers,
Michael

 

[MichaelJ]

For now I am going to crank up the UV filter and let it run continuously for a couple of days.

HI @X3NiTH Yep, running the UV filter continuously for a couple of days (since Friday) did the trick. The water is back to being as clear as I like it to be. Now, the problem is to figure out how much I have to run the UV filter on the timer to keep the water clear. I guess I will have to experiment a bit.

Cheers,
Michael