90 Gallon Low Tech Setup - The Planted Tank Forum
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post #1 of 4 (permalink) Old 08-01-2020, 08:14 PM Thread Starter
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90 Gallon Low Tech Setup

Hello all,

I am currently having quite the difficulty setting up/ establishing my 90-gallon low tech tank. I initially set the tank up back in January 2019 but have not been able to get a handle on it. The tank is a 48" long x 18" width x 24" deep(tall). I originally used Seachem Flourite as a base then capped it with black sand. The filter is a Fluval FX6, the heater is a Finnex HMA-500S Electronic Controller Aquarium Heater, and I currently have the Finnex Planted + 24/7 (48") as my light. I also have a small piece of driftwood in the tank. I use the glass lids that came with the tank to help with evaporation and to help prevent the light fixture from getting water damaged. My goal was/is to keep the tank as low tech/ maintenance as possible using low light-demanding plants while trying to avoid CO2 injection as much as possible.

Initially, I tried using the 24/7 setting of the light fixture with some crypts, jungle vallisneria, java moss, and anubias that I moved over from my old 55 gallon low tech. However, this resulted in a slew of algae problems of various species and practically no plant growth, in fact nearly all of the jungle vallisneria and crypts died, the anubias are still just barely hanging on, but the java moss does relatively well. In addition, the only fish I were able to successfully keep were corydoras and malaysian trumpet snails. I have tried a variety of tetras, bushynose plecos, zebra danios, and RCS but to no avail. This led to me becoming disheartened causing me to neglect the tank.

Fast forward to December of 2019 and I decided to try again. With nearly all of my old plants dead, except for the java moss and some anubias and only the MTS and a handful of corys still around I performed a large cleaning on the tank- manual removal of all algae I could get, 50-75% water change, and changing all of the filter media. I changed the settings of the light fixture to be at max for 4 hours in the morning, a 4 hour off period, then 4 more hours on max in the evening, as opposed to using the 24/7 setting thinking the 24-hour run-time may have been contributing to my algae issues. I purchased a variety of low light-demanding plants such as Bacopa, Rotala Rotundifolia Red, Dwarf Hairgrass, Red Cabomba Piauhyensis Furcata Fanwort, Hydrocotyle Tripartita, Nesaea Pedicellata, amongst others. Also, under the assumption that the flourite may have been drained of nutrients by this point, I used seachem root tabs in areas where I had plants. This time over the period of a few weeks to months most plant varieties slowly melted away and died with the exception of some anubias, java moss, and some crypts. Again another algae explosion of a variety of types, but mainly hair algae. Also, the only fish I was capable of successfully keeping were cory varieties, MTS, nerites and this time amano shrimp also did ok, but other species such as tetras and bushynose didn't last. Over time most other varieties of algae except the hair algae subsided, but this may have been due to the large MTS population I have by this point (my guess is numbering in the hundreds- hard to tell since they're usually burrowed in sand during the day).

My pH remained at around 7.0-7.6 throughout this period (I would like this lower for tetras if possible), my ammonia and nitrites were always zero, and my nitrates were always under 20 ppm, usually under 10 ppm. The temperature remained at about 79 degrees throughout.

So as you can see I haven't had too much luck with the tank to this point. Currently, my thoughts/ concerns are:

1. The strength of the filter may be to blame for the fishkeeping considering it is a very large/ strong filter for that size tank, especially considering it has only one outlet. This may have resulted in stressing non-bottom dwellers out to the point of death. I plan to custom build a spray bar to help diffuse the flow over the tank and hopefully resolve this issue if it is one. Either way I imagine this is a good idea to help circulate water throughout the water column more easily.

2. I'm beginning to wonder if the lighting is too powerful on max for 8 hours a day resulting in the algae spurts causing them to outcompete my plants for nutrients and light. However, the lighting might be too low considering the plants aren't able to outcompete the algae, so I'm not sure which case is more likely. Also, I've always wondered about keeping the glass lids on the tank considering this can reduce the light getting into the tank and reaching the plants closer to the substrate. My guess is the light intensity is too strong as well as the photoperiod being too long so I may try dimming the light to 50-80% and reducing the photoperiod to one 6 hour period. I'd like to keep the lids on if I can to prevent evaporation and to protect the wooden canopy I have over the tank, it has gotten water damaged and mold in the past from evaporation. I'm also concerned the depth/height of the tank might be an issue with the lighting.

3. Are root tabs enough for low light root feeding plants so long as I add more every few months? Or would I be better off dosing liquid ferts, or a combination of the two? Like I said I would prefer the least maintenance possible but if dosing liquid ferts is necessary I will do it.

Any help/thoughts/comments/concerns/etc. would be extremely appreciated. I'm prepared to make one more attempt to establish the planted tank and purchase the necessary equipment (stronger lighting, smaller filter, etc.) if need be, but figuring out where my problems lie is my issue. My plan of attack is to manually remove all algae (again), followed by a 50% water change, cleaning of the filter, changing of the light intensity/photoperiod, and restocking of plants/ root tabs.

I know this is a lengthy post and I appreciate it if you read it and I'm sure there is some information I left out. If there are any more details on the situation that need clarification let me know and I'll be happy to provide them. Thanks for any and all help!
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post #2 of 4 (permalink) Old 08-05-2020, 02:10 AM
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You've mentioned the fish not living long both times you've tried, which makes me think the tank has likely not been entirely cycled this time. Losing plants is one thing, but fish are unrelated to that really and that's a main red flag. Have you tested your water the tank has been fully cycled along the way?

Also, I have the same tank and one thing that helps it get going being a big tank is to start with a TON of plants, especially if you have moderate or heavy fish stock. Heavily planted, with most of the plants being very easy to keep alive that grow fast (bunch stem plants are great, floaters etc). This helps the entire tank stabilize early and then you can remove the unwanted plants and upgrade to other, more desirable plants.

Lastly, root fertilizers are great for plants that like getting nutrients from their roots. I would definitely still using liquid ferts as well however. I'll let other, more advanced folks comment on the specifics there.
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post #3 of 4 (permalink) Old 08-06-2020, 02:39 AM Thread Starter
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Thanks for the input. Both times I started I used (what I thought to be) a large amount of plants. The first time I had tons of crypts and jungle val I was moving over from my 50 gallon as well as some of the other things mentioned. The second time I had that large amount I listed above, with at least 10 or so of each species so it seemed like a lot of plants. The problem is over the course of a few weeks to a month or so most of the plants melted away and died in both instances which makes me think it was a lighting issue, considering I added root tabs and used a fertilized substrate.

As for the fish I agree that something isn't right there. Both times I allowed the tank a month or so after adding plants before adding fish. My ammonia and nitrite were both 0 and my nitrates always stayed under 20 ppm. My pH was around 7.5 because my tap water runs a little high. Also I forgot to mention that I used Seachem prime as my dechlorinator when adding water to my tank. The thing that really confuses me is that corys tend to do fine in the tank as well as inverts which makes me think the issue lies in the water current which primarily affects the non-bottom-dwellers.

What sort of light(s) do you run on your tank since its the same size and for roughly how long each day? Do you ever have any issues with algae or plants melting?
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post #4 of 4 (permalink) Old 08-08-2020, 03:56 AM
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That's a bit odd. The FX6 isn't too overly high power for a 90g tank. I have it and an Eheim 4+ Pro canister on mine and have for a few years. Not sure what's going on there fish wise, but turn the flow down to low and you should be able to easily rule it out one way or another.

As for plants, I would add a ton of hornwort or floating plants to begin. Seems to help keep the initial algae away, again toss after it's established if you want.

Last planted tank I had (last year before switching my main tank to cichlids) I used a planted 24/7 light and just used it on max about 6hrs a day. In the beginning I had to keep to around 4hrs I believe.
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