What happens to substrate PH over time with detritus? - The Planted Tank Forum
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post #1 of 8 (permalink) Old 08-14-2015, 05:06 PM Thread Starter
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What happens to substrate PH over time with detritus?

I was describing a situation in my tanks and a fish store employee suggested something, and I would appreciate knowing how much truth is behind it?

I have moderately planted tanks, one with sand and one with gravel + ecco complete, but basically both inert with respect to ph.

Because of plant density I do not vacuum the substrate significantly, I just let the detritus accumulate from the fish (lightly stocked but some heavy poopers). The substrate is fairly deep in one (2-3").

Over time there has been a slow change in growth patterns, where what had been slow growing plants (crypts, annubias) have gone from slow growing to very active and healthy and spreading and growing fast (relatively).

Other very fast growing plants, especially wisteria and rotala have basically stopped. My Jungle val went from exceptionally fast growing and spreading and now is just getting bigger (wider leaves, wider bases, very little spread). Even the very fast growing hydgo slowed down. The rotala slowed its growth but also now has much smaller leaves (like 1/4 the original size).

All at the same time the other plants are going nuts. All with similar ferts and same light (low tech, no co2, a bit of excel).

The employee's suggestion was that the substrate with the very low flow rates and lots of rotting matter has become much more alkaline, and some plants react well, some poorly. Essentially over time he speculates the substrate environment has changed substantially and that is good for some plants and poor for others.

Is this a reasonable thought?

Can you think of other causes that would cause plants to react as mentioned, specifically crypts and annibias to take off while the normally hyper-speed wisteria just stops? Oh, and one sword also stopped growing and looks ratty a few inches from crypt wendtaii that is now about 10" tall and soccer ball sized.

Bump: I should add details for those who like numbers: PH of the water is about 7.7-7.8, dKH about 4, dGH 6-8 (varies over time).

I fertilize with CSM+B (previously FLourish Comprehensive) weekly, 30ml in 200G of a 2 TBS in 500ml solution, Iron DTPA hangs around .6 to .8 (needs to come down, I overshot a bit last correction, I aim for about .1 to .2), 30ml Excel-strength glut daily, phosphate around 1-2ppm, nitrates about 20-50ppm (depending on water change timing), 78F, relatively strong flow.

RODI water remineralized with Equilibrium to set the dGH, I change water about once a month so in the 3rd and 4th week I add a bit of potassium back in.

Osmecote+ root tabs about every 4" every 3-4 months (I can't tell much difference with or without frankly).

Low level light but in the high range of low (at a guess maybe 15-25 PAR) for two 4 hour periods.

Other than GSA growing on the Annubias, no significant algae (SAE's keep it very clean).


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post #2 of 8 (permalink) Old 08-15-2015, 10:28 AM
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Biological activity (rotting detritus) is going to reduce alkilinity and pH not reduce it. I'd also suggest that unless you are seeing a shift in tank water pH, the substrate pH in unlikely to have shifted dramatically. Not sure what your dosing schedule is like but if if were my tank, I would experiment with increased fertilizer and water changes. Light intensity is also another variable. Crypts and anubias seem to do quite well in light too low to grow anything else...No answers for you, at the end of the day, you'll have to experiment with the "plant growth inputs", fertilizer, light and CO2, to see which one has an effect.


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post #3 of 8 (permalink) Old 08-15-2015, 02:34 PM
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I had the same problems with substrate tanks. Crypts and Anubias did fine, but wisteria and practically anything else I put in my tanks stunted, got covered in algae, and looked bad. I have since quit using any substrate in my 4 10g tanks, taken away the filters and air as well, and have incredible success. Plants need a clean tanks as well as fish to grow to their potential. Substrate is problematic. I think over time it ruins and needs a complete change or cleaning, which is no fun. You can go to my new website and check out my methods and maybe incorporate some of them into your tank and see if it helps. It really made the difference for me, and now I can enjoy watching the flourishing tanks! Warning: The extreme nature of my tanks restricts the types of fish you may be able to keep. My methods are explained thoroughly. Hope it helps! http://aquariumexperiments.com

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post #4 of 8 (permalink) Old 08-15-2015, 10:27 PM Thread Starter
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Dave, that kind of thing (getting it completely backwards) is why i try to doublecheck informaiton picked up in stores (or on the internet).

BTW, before posting this, I also tried testing the PH by taking a long stiff tube and sucking up some water, but it was so discolored by debris that it was hard to judge color. My guess from the colors is that it was lower PH, but I was quite unsure (and also not sure what happened if I was well off the scale in one direction).

I'm always experimenting, both on more short terms to get the right level when I can test for them, but also to see plant reactions. This current trend is much longer term. Usually in a few weeks I can see some change from a change in ferts (I do not much play with the lighting), but this is a longer term trend that has survived several changes in fertilization.

AWolf - I looked through your documentation, and there are some interesting thoughts there especially with respect to simplifying. Certainly the more variables the harder it is to make what one does more science and less wishful thinking. I'm not sure I am ready to head down that path however. I'm hoping for a more natural balance that has a lot of built in resilience in the same way a natural pond or river will. I can never really get there with gallons versus hectares of water, but at least directionally that is my goal.

Dave, as to whether there are fert issues, the one thing that makes me think something more is going on is this wisteria.

That shot is from mid-February. Notice in the center slightly photo right that huge plume of wisteria (the tank is 28" high). That was about the 3rd grow-in of it. It started in August (+/-) of last year, after 2-3 months it would grow huge and start becoming more cloud than plant. I would cut about 3/4 of the plant out, and within a month or two it was back near the top of the water.

This is the same area today.

Since the last trimming, the foliage has actually died back to maybe a half or a third the size from when I trimmed it. The leaves look stunted and a bit unnatural. About half way through this slow death, I added a couple of root tabs just to see if it mattered; no change.

Now while you're looking at the feb shot, notice on the photo-left the size of the crypt wendtaii. Here's today with the rocks in the same size/place:

They are probably 3 times the size as a few months earlier.

Here's a closeup of the rotala (I don't have a good wide survey shot from before).

Note the well formed and full leaves. It was growing vertically about as fast as the wisteria, and I would cut it off down load to make it branch and fill in, and replant what I cut. Then somewhere about 3-4 months ago, it started doing this:

Slow growth vertically, and tiny, tiny leaves. Now I will add that I had a suspicion I had too much potassium (and yes I know that is supposedly almost impossible), so I cut way back on that dose, and the rotala looks slightly better, but that may be wishful thinking. It is still nowhere near where it was.

Now this is a different tank, but one I maintain very similarly. Notice the sword in the right corner. It is growing well and I had some concern it would eventually get too big. Leaves are well formed and not eaten.

Here's the plant today, a much closer shot.

The plant has actually shrunk, the leaves are getting thin and are now being picked at by the plecos, who previously would leave them alone. It's also more yellow. It has a couple fresh root tabs from about a month ago also once I started seeing this.

Final image is from the crypt and java fern and a glacially slow annubias that is beside the sword. Compare to the survey shot and log, and you can see how well they have done in the same time frame.

I realize some do better in less rich conditions, but that includes things like the wisteria. If it was doing well also, and it was more demanding plants like the sword doing poorly. But the wisteria is practically dead.

Any thoughts given the photos?


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post #5 of 8 (permalink) Old 08-15-2015, 11:13 PM
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Linwood..Lovely tank! I am considering taking my NFSA tank method to larger scale, like a 40-55 gallon. But I will need so many plants. Still, I wonder if it would work as well on larger scale. Can't imagine why it wouldn't. Maybe I can find a long low 55 to replace my four 10g's. That would be so great.

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post #6 of 8 (permalink) Old 08-16-2015, 12:34 PM
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Balancing the Water Chemistry

Hello Lin...

Tank keeping is really pretty simple. It's all about the water. Follow an aggressive water change routine and you'll have a balanced tank. If you're not already, work up to the point you're removing and replacing 50 to 60 percent of the tank water weekly. More in this case is always better. But, no slacking.

By flushing a lot of pure, treated tap water through the tank, you remove excess nutrients and maintain a steady water chemistry. This is all the fish and plants need.


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post #7 of 8 (permalink) Old 08-16-2015, 07:16 PM
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Linwood, I know your tap water is liquid rock, and water changes are difficult and impractical due to needing to use RO/DI water and buffers.

I wonder though, if you really couldn't do a planted tank with your tap water. Mine is pretty hard too, but it works well when I keep changing it. Fresh water. Fresh nutrients. Fresh trace elements.

I pitch 80% of the tank water weekly, and growth has remained phenomenal even though some species didn't work out in my setup.
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post #8 of 8 (permalink) Old 08-16-2015, 07:36 PM Thread Starter
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BBradbury and BigJay180, I know there's a common feeling that water changes fixes everything, and I am not knocking water changes, but not all problems are solved that way.

BigJay180, consider your comment "growth has remained phenomenal even though some species didn't work out in my setup". Well, that's the case here, but I am observing that it changed over time. Some species that did well are now doing poorly, and vice versa. The presumption is something (probably something that develops over time) has changed, favoring some plants more than others.

If simply some plants started doing poorly, without a reciprocal improvement in others, I would agree this is a problem that needs a "fix" and that toxicity of some sort may be at play.

But this seems more like a shift of environment, like a flower bed going from shade to sun, where different plants thrive and fail.

I'd like to understand what it is. Simply putting it back is not necessarily a solution. For example, in this case I like crypts better than wisteria by far, so if I had to pick -- the current situation is better than when wisteria ran wild. ANd frankly I like them better than the sword. I've also seen some stellar growth in one tank of val's, after sitting still for ages they started spreading so fast you can almost watch them grow.

Maybe I don't have to pick. Maybe some aspect (say the concentration of unobtainium has increased) maybe I can adjust to a more middle ground and still get the benefits and stop hurting other plants. But that implies awareness of what is happening.

My GUESS at the substrate is because it seems likely that the water column itself is indeed more likely to be kept somewhat stable by water changes, but since I cannot really vacuum, the substrate is an area where cumulative "stuff" might change the environment strongly over time. Maybe.


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